Download Abstract: The selective introduction or modification of functional groups in complex molecules has been a longstanding challenge in catalysis. Our group has developed practical methods for the catalytic functionalization of C-H bonds with boranes, silanes and azides. These studies have resulted from a general strategy in which a single C-H bond functionalization reaction that installs a temporary functional group can be used to create range of products. This research has led us to seek new systems for the functionalization of C-H bonds in complex molecules and to develop new classes of catalysts that create new capabilities of achieving selective catalysis with transition metal centers. This lecture will present recent directions of research in our group toward discovering selective C-H bond functionalization reactions of both small and complex molecules. The design and selection, as well as the intimate mechanism, of catalysts and catalytic reactions for selective functionalization processes will be presented.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Our group is interested in exploring cytochrome P450 catalysis as a strategy to mediate the selective, late-stage transformation of unactivated C(sp³)−H bonds in organic molecules. P450 enzymes constitute attractive catalytic platforms for the oxyfunctionalization of organic compounds, but the lack of effective strategies to refine their reactivity and site-selectivity currently limits their utility for synthetic applications. To tackle this problem, efforts in our laboratory have focused on implementing systematic, rationally-driven methodologies to modulate, predict, and ultimately, fine-tune the selectivity of these enzymes. In this talk, we will give an overview of our recently introduced 'P450 fingerprint'-based methods to rapidly map the active site configuration of these enzymes and predict their reactivity toward a variety of target substrates. Leveraging these methodologies, we have begun to evaluate the potential of P450-mediated chemoenzymatic C−H functionalization as a new, enabling strategy for the late-stage elaboration and optimization of bioactive natural product scaffolds. In the second part of the talk, we will present our recent progress toward developing P450s into efficient catalysts to promote the selective amination of aliphatic C−H bonds via nitrene C−H insertion, a transformation which has so far been restricted to the realm of synthetic transition metal catalysis. The presentation of these results will be accompained by a discussion on our current mechanistic understanding of these reactions and the implementation of mechanism-guided rational design strategies to enhance the C−H amination reactivity of these biocatalysts.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Continuous flow processes form the basis of the petrochemical and bulk chemicals industry where strong competition drives the need for highly performing, cost effective, safe and atom efficient chemical operations. Fine chemicals, such as drug substances and active pharmaceutical ingredients (APIs), are generally considerably more complex than commodity chemicals and usually require numerous, widely diverse reaction steps for their synthesis. The advantages of continuous flow processing are increasingly being appreciated also by the pharmaceutical industry and, thus, a growing number of scientists, from research chemists in academia to process chemists and chemical engineers in pharmaceutical companies, are now starting to employ continuous flow technologies on a more routine basis. Owing to the small reactor volumes, the overall safety of the process is significantly improved, even when harsh reaction conditions are applied. Thus, microreactor technology offers a unique way to perform ultrafast, exothermic reactions, and allows the execution of chemistries which proceed via highly unstable or even explosive intermediates. In this lecture, contributions from our research group in the field of continuous flow processing will be highlighted. Emphasis will be given to highly atom efficient and process intensified chemical transformations useful for the synthesis of APIs or key intermediates that rely on C–H activation and related chemistries including photoredox catalysis, catalytic cross-dehydrogenative-coupling (CDC), the direct arylation of arenes, Fenton chemistry, and the C–H activation of methyl groups using Pd/O₂.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Two methods for functionalization of C-H bonds will be presented: 1) the C-H functionalization of substrates such as amines, nitriles, ketones, isocyanates alpha to heteroatoms with transiton-metal catalysts gives alpha-transition-metalated intermediates, from which various useful methods for unique and selective carbon-carbon bond formation can be constructed. Acid-base ambiphilic transition metal catalyst would be a future key catalyst; 2) the C-H functionalization by bio-inspired metal catalysts and biocatalysts with molecular oxygen or peroxides provides useful methods for catalytic C-H oxidative functionalizations of various substrates such as amines, amides, and even non-activated hydrocarbons under mild conditions.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Advances in achieving site-selectivity in small molecule catalyzed C–H oxidations without the use of directing groups will be discussed. The first approach is the development of small molecule catalysts that are sensitive to the inherent electronic, steric, and stereoelectronic differences between C–H bonds in complex molecule settings. A second, complimentary approach termed "trajectory restriction" uses minimal steric blocking elements incorporated into a small molecule catalyst to increase catalyst/substrate non-bonding interactions, while maintaining structural flexibility such that substrates of diverse topologies are accommodated. Using a combination of these approaches, unprecedented sitedivergent diversification of complex bioactive molecules like artemisinin can now be easily achieved. To maximally benefit from these approaches, a user-friendly catalyst reactivity model that calculates and even predicts the major site of oxidation as well as the magnitude and direction of the site-selectivity in complex substrates as a function of catalyst has been developed and will be discussed.

Venue: B-2285, Jean Brillant Building, UdeM

Venue: Cafeteria Chez Valère ((B-2294), Jean Brillant Building, UdeM

Download all poster titles and abstracts: Poster boards (#PO36 to #PO70) will be displayed in the corridors adjacent to Room B-2285. Presenters will be able to set up their posters at any time during the day. For inquiries, please see our volunteers.

Venue: Corridors of B-2285, Jean Brillant Building, UdeM

Download Abstract: Doravirine is non-nucleoside reverse transcriptase inhibitor (NNRTI) currently in phase III clinical trials for the treatment of HIV infection. Herein we describe a robust kilo-scale synthesis for its manufacture used to supply pre-clinical and clinical supplies. The structure and origin of major impurities was determined and their fate and purge studied. This resulted in a re-design of the route to introduce the key nitrile functionality via a copper catalyzed cyanation in order to ensure all impurities were controlled to an adequate level. The limited availability of 3-chloro-5-iodo-phenol prompted us to develop a metaselective iridium catalyzed C–H borylation-oxidation sequence which readily afforded the desired phenol. Overall, the synthesis could be scaled to prepare Doravirine in >90 kg batches and was used to prepare all pre-clinical and clinical material up to phase III. The synthesis affords high quality material in a longest linear sequence of 6 steps and 37% overall yield.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Several first row transition metal catalysts employing iron, cobalt, and nickel with non-innocent ligands have been synthesized and their ability to catalyze dehydrogenation of alcohols and amines, as well as their ability to hydrogenate ketones and quinolines, has been comparatively evaluated. The scope and mechanism(s) of these reactions have been examined. Also, the use of an alcohol dehydrogenation catalyst along with an Aldol condensation catalyst has led to a new route to convert ethanol directly and cleanly to 1-butanol.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: The oxidative intramolecular Pd(II)-catalyzed amination or oxylation of unsaturated N-sulfonyl carbamates, N-sulfonyl carboxamides1 and carboxylic acids takes place through the involvement of cyclic aminopalladated or oxypalladated intermediates. These intermediates may subsequently evolve along different pathways such as distocyclic or proxycyclic β-H elimination, oxidative oxylation, or intramolecular carbopalladation, as a function of the nature of the substrate and/or the reaction conditions. However, when the above reactivities are inhibited, the palladated intermediates are only off-cycle intermediates in equilibrium with the initial substrate. This hurdle opens the way to alternative oxidative cataytic cycles, the most relevant one being the C-H activation of the allylic position. Our experimental studies in concerto with DFT calculations allow putting forward an unifying mechanistic scenario that rationalizes the ensemble of the observed results in this field.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: The transition metal catalyzed direct functionalization of unreactive C–H bonds represents one of the most powerful tools for sustainable syntheses and opens a new route to pharmaceuticals and natural products. A general drawback is requirement of stoichiometric external oxidant, such as Cu, Ag salts and BQ, to complete the catalytic cycle, which would produce a stoichiometric amount of the reduced external oxidant as waste and reduce the overall "greenness" of the process. Therefore, we have been interested in developing some strategies to avoid the external oxidants, such as "internal" oxidant as a directing group and starting materials, and redox process of substrates.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Various C–C bond formation reactions, such as arylation, alkylation, benzylation, allylation, and carbonylation with the cleavage of C–H bonds have been reported to date. However, the methylation of C-H bonds continues to remain an undeveloped area, compared with the other type of C–C bond formation reactions. Although the methyl group is one of the simplest functional groups, the introduction of a methyl group at a C–H bond can have a significant effect on the biological and physical properties of a drug, an effect that is known as a magic methyl effect. New types of Nicatalyzed methylation of C–H bonds will be discussed.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Before 2012 only a few scattered examples of C–H insertion reactions in gold catalysis existed. Then independent work of Liming Zhang's and Hashmi's groups demonstrated that unactivated sp³-C–H bonds can efficiently react with highly activated gold carbene species. From this a rich and versatile chemistry evolved. Now entirely new catalytic intra- and intermolecular C–H insertion processes of highly reactive gold(I) intermediates, both from dual activation and activation by only one gold center, will be presented.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: The direct arylation of pyridine derivatives using non-precious catalysts is underdeveloped but highly desirable due to its efficiency to access important motifs while being extremely cost-effective. An unprecedented nickel-catalyzed C-3 direct arylation of pyridinium ions was developed to provide a new approach to valuable 1-azafluorene pharmacophore frameworks. This transformation is accomplished using air-stable nickel catalyst precursors and tolerates a variety of substituents. Computational studies were performed to further understand the unique reactivity of the pyridinium ions under these conditions and the reaction pathway which leads to the products obtained.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Considering the importance of chiral molecules, a continuous search for original strategies for asymmetric synthesis presents a great scientific challenge. A direct functionalization of C–H bonds opens new avenues in this field as now unprecedented retrosynthetic disconnections may be envisioned to construct stereogenic scaffolds from simple starting materials in a step- and waste-economic manner. Recently the potential of the chiral sulfoxide to play the role of both, a chiral auxiliary and a traceless directing group, in C–H activation reactions, has been evidenced. The sulfoxide-directed asymmetric C–H functionalization enabled very efficient and highly stereoselective synthesis of various axially chiral biaryls via direct C–C, C–O, and C–X couplings. The synthetic utility of this approach could by illustrated by performing a straightforward synthesis of biologically relevant Steganone scaffold. The latest results shows also that chiral sulfoxide directing group is also a promising tool to allow challenging, asymmetric C(sp³)-H functionalization.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: The formation of dopaquinone during melanogenesis, catalyzed by the ubiquitous enzyme tyrosinase, involves the oxygenation of a phenolic C–H bond via a side-on peroxodicopper(II) species made by reaction between Cu(I) and O₂ at 25 °C. Performing model Cu(I)/O₂ reactions in solution, however, leads to complexes that are thermally unstable (−80 °C) and difficult to study. By substituting O₂ for isoelectronic nitrosoaryl compounds (Ar–N=O), the chemistry is similar but the ensuing Cu/nitrosoaryl complexes are stable at room temperature, and are thus more easily characterized and used. Upon reaction with a phenolate, nitrene transfer occurs cleanly to yield a Cu-iminoquinone complex, which releases an aminophenol under reductive work-up. This reaction is analogous to the formation of quinones in Cu/O₂ chemistry, and comparison with our mechanism of the catalytic aerobic ortho-oxygenation of phenols provides hints on how to further develop this one-step C–H bond amination.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: C–H amination is a very elegant, atom-efficient and potentially versatile approach to forge C–N bonds. Catalytic pathways that involve bioinspired odd-electron mechanisms have gained momentum in the last few years, with much emphasis currently on open-shell transition metal species as the locus of radical reactivity. This approach requires the use of paramagnetic metal ions (e.g. high-spin FeII, CoII) to generate metal-bound substrate radicals. Redox-active ligands have been overlooked as a tool to invoke radical character onto metal-bound substrates. Palladium(II) is normally not disposed to induce odd-electron chemistry onto bound substrates, e.g. organoazides. Employing a novel redox-active pincer ligand, we have recently reported the first example of stoichiometric ligand-to-substrate single-electron transfer, utilizing the coordination sphere of redox-inert Pd(II) as substrate-binding platform. This concept proved competent for the intramolecular benzylic C–H amination of organoazides via nitrene radicals. This contribution will discuss the overall strategy of ligand-mediated odd-electron mechanisms for C–H amination on Pd as well as Fe, based on experimental and computational insight.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Arylboronates have become a prominent class of organic reagents not only for the well known Suzuki- Miyaura coupling, but also as valuable synthons for delivering various functional groups. Although the current commercial technology heavily relies on using either palladium-catalyzed borylation or electrophilic borylation of stoichiometic Grignard reagents, iridium-catalyzed C-H borylation provides an atom-economical alternate pathway for creating these valuable starting materials that has been the source of significant investigation.1 Despite the attractiveness of this method, hindering factors such as inconsistent reactivity, unstable and expensive precursors, and tedious pre-activation protocols can create complications limiting its utility. Our group recently disclosed a stable iridium precatalyst based on less expensive precursors to mitigate these issues and increase the practicality of this powerful class of C-H functionalization catalysts. The merits and limitations of these methods will be discussed in light of the alternate technologies.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Several representative enantioselective alkaloid total syntheses and related methodologies will be discussed. The focus of this research program is the development of new synthetic strategies for rapid generation of molecular complexity guided by biogenetic considerations. These syntheses feature new stereo- and chemoselective reactions that enable maximum use of the inherent chemistry of key intermediates. Examples involving strategic C–H functionalization in complex settings will be discussed.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Visible light photo(redox) catalysis has emerged as an efficient strategy in organic synthesis as it employs readily available and easy to handle catalysts in combination with visible light and can be applied to a variety of transformations. The potential of photo(redox) catalysis calls for further exploration, as visible light is a safe, abundant, eco-friendly and readily available energy source which meets demands for more economic and environmentally-friendly processes. The potential of visible light in promoting catalytic reactions has been validated and, with the introduction of photo(redox) catalyzed processes, new horizons are open for accomplishing traditional chemical reactions in a more expedient manner and for introducing concepts for performing highly demanding transformations such as fundamental C-H and C=C bond functionalizations. In this presentation our introduction to visible light photo(redox) will be shown and new and valuable transformations will be highlighted. Additionally, efforts to delineate the general requirements for visible light photo(redox), as well as combined catalysis processes, will be outlined.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: By avoiding tedious procedures to prepar for organic halides, hydrocarbonds has been directly applied for cross couplings to take place of oranohalides under oxidative conditions. Starting from C-Hs, highly selective halogenations, oxidative coupling with aryl boronic acids, aryl silanes, Grignard reagents, and even another molecule of arenes were approached. Benzylic and allylic C-H activations were also conducted to construct C-C bonds through oxidative coupling procedures.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Two different classes of novel ligands are developed to drastically accelerate Pd-catalyzed C–H activation reactions. These ligands enable the activation of C–H bonds that are near or far from a functional group, demonstrating the feasibility of achieving selectivity by recognizing the distal and geometric relationship between different C–H bonds and existing functional groups. Enantioselective C–H activation reactions are also made possible by using chiral version of these ligands, providing new disconnections for asymmetric synthesis.

Venue: B-2285, Jean Brillant Building, UdeM

Venue: Cafeteria Chez Valère (B-2294), Jean Brillant Building, UdeM

Download Abstract: Isoprekinamycin (IPK) belongs to the rare benzo[a]fluorene class of natural products, and has been shown to possess potent antibacterial and antitumor properties. IPK has previously been prepared in an 18-step linear sequence. Herein we present our total synthesis of isoprekinamycin, which has been achieved in only 8 steps. The key step in this synthesis involves an unprecedented 'double DreM' cyclisation, allowing the construction of both the beta-naphthol and fluorenone ring systems in a single operation via the sequential functionalization of C(sp³)–H (5→4) and C(sp²)–H (4→2) bonds. The versatility of this route is further exemplified by the conversion of intermediate naphthol into a second natural product, prefluostatin, by simple deprotection with BBr₃.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: This presentation will describe the development of novel reactions for the formation of both carbon– carbon (C–C) and carbon–nitrogen (C–N) bonds via dual C–H/C–H or C–H/N–H activation mechanisms. Each of the reactions involves dual C–H/C–H or C–H/N–H activation mechanisms and an organic or inorganic oxidant. Ultimately, regioselective oxidative arylation and amination reactions were developed, allowing the presenter and his research team to map the chemical reactivity of a variety of arenes and amines in oxidizing conditions.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Benzo-fused heteroarene frameworks exist in various organic materials and pharmaceuticals. Therefore, development of straightforward and effective synthetic methods leading to them is of fundamental importance. Among the most promising strategies is the transition metal-catalyzed dehydrogenative annulation of aromatic substrates possessing a directing group with alkynes and alkenes through regioselective C−H bond cleavage. Besides σ-coordinating functions involving oxygen, nitrogen, sulfur, and phosphorus atoms, π-electron units such as alkenyl, alkynyl, and aryl functions have been found to act as directing groups for ortho C−H functionalization. Thus, it may be conceived that highly fused polycyclic heteroarenes can be easily prepared by employing the π-coordination mode. In this symposium, we report such annulation reactions on arylated heteroarenes and related substrates under rhodium(III) catalysis.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Transition-metal-catalyzed C–H functionalizations has greatly complimented to traditional organic synthesis that involves atom and step saving processes with high functional group compatibility. Yet most of the known C–H functionalization was carried out using noble late transition metals, which are very expensive and hence transformation from academia to industry is very unlikely. Due to fast depletion of noble metals and cost efficiency, we need an alternative catalyst that are low cost, earth abundant and match or surpass the activity of noble metals. Certainly cobalt be the first choice, due to above mentioned factors and in addition, it possess variable oxidation state and hence it may have unique reactivity than its second row and third row counter parts. In this lecture we disclose some of our recent results on C–H bond functionalization using air stable, low cost, versatile cobalt (III) catalyst for C–H bond functionalization. We will discuss in detail C–H bond annulation, sequential C-H activation/oxygen atom transfer, and C-H bond allylation, etc. Our preliminary experiments on mechanistic investigation and DFT calculations suggest that C–H activation proceed through an inner sphere mechanism and oxygen atom transfer will be the rate determining step.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Methods to form polycyclic heterocycles through the construction of C–Y bonds (Y = C, N and O) are of vital importance for the synthesis of molecules for applications in pharmaceuticals and materials science. Dramatic progress has been made with rhodium-catalysed oxidative functionalisation of C–H bonds with high selectivity and functional group tolerance without the need for pre-functionalisation. Here we present some of our mechanistic investigations of Rh-catalysed carboxylate assisted C–H functionalization of pyrazoles. We will show that the nature of the C–H activation step is controlled by the solvent and that C–H activation or reductive elimination can be rate determining. The importance of the computational methodology to accurately model the experimental results will also be discussed.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: The C–H functionalization is a perennial topic of interest for organic chemists, it is a great challenging task to accomplish highly selective C–H bond functionalization under mild conditions. In the past a few years, the directed alkylation, cyanation, oxidation, amination, acylation and phosphonation of C–H bond were realized in our laboratory, with transition metal（Au, Re, Rh, Cu, etc.）catalysis or metalfree conditions. With those transformation methods, different kind of heterocyclic compounds were effectively constructed. Owing to its significant advances in energy-saving and environmentally benign features, visible-light photoredox catalysis has witnessed rapid development and attracted considerable attention in both academia and industry. The incorporation of a fluorinated group into organic molecules is particularly intriguing because of its significant applications in the life sciences. Recently, our group achieved visible-light-induced trifluromethylation and difluroalkylation with different kind of fluro reagents, several kinds of fluorinated compounds were synthesized efficiently.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: The two past decades have seen the establishment of several synthetic methodologies of transition metal-catalysed direct C–H bond functionalization of major classes of heterocycles and dedicated mainly to standard substitutions. This young field of chemistry goes now to a second phase of maturing towards structural and functional diversity to meet directly a strong echo in natural product, pharmaceutical and material sciences. In this context, α-alkoxylated cinnamic acids and 4,4'-arylidene imidazolones have been evaluated to propose original access towards heteroarylated vinylethers as well as famous GFP and Kaede protein fluorophores.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Introduction of trifluoroalkyl groups into aromatic molecules is an important transformation in the field of organic and medicinal chemistry. The fluorine containing functional groups (mainly trifluoromethyl, trifluoromethoxy, trifluoromethylthio) are often used order to their effect on lipophilicity and metabolic stability. Due to the presence of fluorine atoms the electronic properties of the molecules also change and allow further reactions on multifunctionalized aromatic cores. However, the direct installation of fluoroalkyl groups onto aromatic molecules still represents a challenging and highly demanding synthetic task.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: With considerable progress in medicinal chemistry, the construction of heterocycles has receiveed increasing attention in the past decades. In particular, N-heterocycles such as indoles, indolines, indazoles, and cinnolinones are widely found to be biologically relevant scaffold in natural products, pharmaceuticals, agrochemicals, and functional materials. Therefore, the directing group-assisted Nheterocycles synthesis via C–H bond activation is highly attractive in pharmaceutical industry. Recently, our groups reported the rhodium-catalyzed tandem heterocycle formation and functionalization via C–H activation reaction of anilines, hydrazines, azobenzenes, and etc. Moreover, we recently focused the construction of other N-heterocycles via tandem C–C bond formation followed by intramolecular cyclization. We herein describe a brief summary of our recent works and present progress works to synthesize other biologically relevant heterocycles via C-H activation.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Direct C–H bond functionalization, and cross-coupling reactions are considered to be among the most valuable and powerful tools for constructing C–C bonds in the synthesis of complex molecules. The Fujiwara-Moritani (oxidative Heck) reaction was discovered in 1967; however, it was unnoticed for a long time due to the lack of the regioselective control. In continuation of our ongoing work on the coupling reactions using in-house developed ligands, we will discuss our recent success on the synthesis of highly functionalized carbazoles from NH-indoles/(E)-3-styryl-1H-indoles via palladium-catalyzed triple/double successive C–H activation.

Venue: B-2285, Jean Brillant Building, UdeM

Participants whose registration includes the conference banquet will be driven by bus to board the Bateau Mouche that will cruise the St. Lawrence River (boarding at 6:30 p.m. at the Old Port of Montreal).
Venue: Jacques Cartier Quay, Old Port of Montreal, St. Lawrence River.

Download Menu and Directions: We suggest a casual attire for dinner cruises to enhance your experience on the Bateau-Mouche. Appropriate clothing for the air conditioning is also recommended.
Venue: Jacques Cartier Quay, Old Port of Montreal, St. Lawrence River.

Download Abstract: In recent years, Pd-catalysed direct arylation of heteroaromatics has become a popular method for generating carbon-­‐carbon bonds. In many cases, such couplings can be performed using as little as 0.1-0.01 mol% of Pd(OAc)₂ as catalyst precursor without phosphine ligand. Moreover, a wide variety of substituents on heteroaromatics are tolerated. In general alpha-arylations of heteroaromatics such as furans, (benzo)thiophenes or pyrroles are favored. However, the regioselectivity of such arylation reactions can be modified by the heterocycle substituents and also by the nature of the coupling partner, allowing either a better control or even a drastic change in the regioselectivity of such arylations. We will ouline some of the recent developments concerning the control of the regioselectivity and the functional group tolerance of such direct arylations.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: A variety of organometallic Ir(I) and (III) precursors undergo oxidation to give Ir(IV) oxo complexes that act as resting states for oxidation catalysis, either hydrocarbon oxidation or water oxidation. Hydrocarbon oxidation proceeds with retention of configuration at carbon, consistent with a concerted oxene type insertion. For one such precursor, the Ir(I) dicarbonyl shown below, structural study required a diol crystallization agent which hydrogen bonds to the alkoxide lone pair.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Herein, we disclose the sequential functionalization of 5-membered ring heterocycles. By employing a pH sensitive directing group both directed and non-directed C-H activation pathways are available, providing access to 2,3,4- and 2,4,-5 substituted thiophenes. Moreover, during the optimization process we discovered that the C-H arylation could be performed in water, and that using a surfactant greatly improved the yield and mass recovery. We believe that the use of directing groups with an on/off switch offers a potentially powerful means of generating diversity around medicinally relevant cores.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: The use of Au(I) and its ability to directly C-H activate 2-bromo-3-hexylthiophene to form a reactive monomer species, bypassing the typical Grignard monomer formation from a dihalogenated thiophene, is investigated. Addition of PEPPSI-iPr as a palladium catalyst source in the presence of the resultant aurylated thiophene monomer yielded poly(3-hexylthiophene) as observed by both NMR and GPC. Studies on the growth of these polymers show linear dependence between M_n and monomer conversion, low dispersities, as well as M_n predicted by catalyst loading, which is supportive of a living-type chain growth mechanism. This Au-Pd system represents a novel methodology for incorporating C-H activation into the synthesis of P3HT with control over M_n.

Venue: B-2285, Jean Brillant Building, UdeM

Download Abstract: Suitably selected combinations of main group Lewis acids and bases constitute frustrated Lewis pairs (FLPs) were shown to activate hydrogen. This has allowed the development of unprecedented metal-free catalytic hydrogenations of C=N bonds, anilines, N-heterocycles, olefins, polyaromatic hydrocabons and most recently ketones and aldehydes. This conceptual advance has been furthered leading to the development of electrophilic phosphonium cations (EPCs). These species prove to be highly Lewis acidic species that can effect CF bond hydrodefluorination catalysis. In addition, these Lewis acids are useful for hydrosilylations, dehydrocouplings, ketone deoxygenation and in FLP hydrogenations. More recently, we have extended the reactivity of EPCs to effect the catalytic Fiedel-Crafts arylation of CF3 groups as well as benzyl fluorides. Such reactivity has little precedent and provides a new and highly variable approach to organic derivatizations. The implications of these findings for applications of main group species in catalysis is considered in this lecture.

Venue: B-2285, Jean Brillant Building, UdeM