<b><i>Abstract</i></b>: Through an approach that relies mostly on mechanistic insights and systematic examination of ligand effects, we have discovered a number of protocols for Ni(II)-catalyzed enantioselective hydrovinylation (HV) reactions of vinylarenes, selected 1,3-dienes, strained olefins and used these reactions for the totally stereoselective syntheses several important compounds including pseudopterosins and trikentrins. However, simple 1,3-dienes, a highly versatile class of substrates, failed the Ni(II)-catalyzed HV giving poor regio- and enantioselectivity. While trying to find solutions in asymmetric HV of 1,3-dienes, we recently discovered that Co(II)-bisphosphine complexes show much improved regioselectivity with broader functional group compatibility (e. g., silylenolethers, enol acetates) and, hence increased synthetic utility. Both linear and cyclic 1,3-siloxydienes gave synthetically valuable enantiopure surrogates on HV with excellent yields and enantiomeric excess, which were further subjected to a variety of electrophilic reactions including alkylation, aldol and Michael reactions (Scheme 1) to generate new carbon-carbon bonds. Because of the outstanding functional group compatibility of the Co(II)-catalyzed HV, we hope this chemistry will provide access to a wide variety of ubiquitous enantiopure 1,4-siloxydienes, which can serve as versatile intermediates for further design and development of many biologically active molecules.

Asymmetric hydrovinylation of siloxydienes: Making enantio-pure nucleophilic synthons

249th National Meeting (2015)

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