Enantioselective Catalytic Boronate Reactions

Boston University (Charles River Campus), Boston MA

Investigators

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Abstract

DESCRIPTION (provided by applicant): The development of new chemical methodologies is an important objective of organic synthesis. An area that continues to inspire chemists is the chemistry of organoboranes and boronates. The unique properties of boron and the ability to activate organic boronates to deliver carbon nucleophiles has yielded an impressive array of chemical methods and processes. We will extend the ability of organoboranes and boronates to deliver carbanion equivalents in novel condensation reactions including chemoselective carbonyl condensations and multicomponent reactions. The reactions will be rendered asymmetric through the development of asymmetric catalysts and chiral boronate reagents and the utility of the methods developed demonstrated by the asymmetric synthesis of pharmaceuticals and natural products. Significant advances have been made in the mechanistic understanding of boronate activation via ligand exchange with chiral diols. We will use the mechanistic insight we have obtained to expand the repertoire of reactions catalyzed by dynamic ligand exchange processes to include acyl cyanides as electrophiles, borono-Petasis reactions, and ortho-quinone methide chemistry. Our continued interest in reaction discovery has led to the identification of chiral diol acid catalysts capable of promoting the enantioselectie addition reactions to acetals. We seek to explore this reactivity and expand it to include types of functionalized nucleophiles in additions to oxoniums and iminiums and boronate hetero-Diels-Alder reactions. Goals of the research program include developing a breadth of reactivity, providing access to novel chiral blocks, and new reaction development. Bond constructions are selected to access chiral synthetic intermediates that could be used in the construction of pharmaceuticals and natural products. The results will transform the way boronate nucleophiles are utilized in enantioselective synthesis.