Sheppard Group – Professor Product Portal

Professor Tom Sheppard

Our laboratory is interested in the development of new synthetic methodology and its application to the synthesis of potentially useful molecules. Our research work is spread across a wide range of different areas including transition-metal catalysis (gold, palladium), organoboron chemistry, organocatalysis, multicomponent reactions, and sustainable chemistry.

A common theme in many of the ongoing research projects is the development of new methods for activation or formation of carbon-oxygen bonds. Within this class of reactions, the direct synthesis of amides from carboxylic acids and amines is one of the most important and commonly used reactions in organic chemistry. In our laboratory, we have reported the use of simple borate esters for the direct catalytic formation of amides from a wide variety of carboxylic acids and amines. In particular, B(OCH₂CF₃)₃ is highly effective, and can be used for coupling pharmaceutically relevant substrates containing heterocycles and other functional groups. It can even be employed for the catalytic direct amidation of unprotected amino acids. In most cases, the amide products can be purified using a simple solid-phase work-up with acidic, basic and boron-scavenger resins without the need for an aqueous work-up or chromatography. The reactions are readily scalable to obtain multigram quantities of material, and are considerably more efficient than most other amidation methods (PMI as low as 5 for the synthesis of an amine on 20 g scale).

Other recent work in the group has included the development of a range of catalytic transformations of propargylic alcohols, largely using the PPh₃AuNTf₂ catalyst originally developed by Fabian Gagosz. Efficient methods have been developed for the gold-catalyzed conversion of these readily available starting materials into enones, 3-alkoxyfurans and dihalohydroxyketones; direct substitution of the propargyl alcohol with a variety of nucleophiles can also be achieved using either a silver catalyst or a simple Brønsted acid.

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