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Catalytic enantioselective protoboration of disubstituted allenes. Access to alkenylboron compounds in high enantiomeric purity.

ABSTRACT: Proto-boryl additions to 1,1-disubstituted allenes in the presence of 1.0-5.0 mol % of chiral NHC-Cu complexes, B2(pin)2, and t-BuOH proceed to afford alkenyl-B(pin) products in up to 98% yield, >98:2 site selectivity, and 98:2 er. The enantiomerically enriched alkenylboron products can be converted to otherwise difficult-to-access alkenyl bromides, methyl ketones or carboxylic acids. What's more, the corresponding boronic acids may be used in highly stereoselective NHC-Cu-catalyzed allylic substitution reactions.

SUBMITTER: Jang H

PROVIDER: S-EPMC4156252 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Catalytic enantioselective protoboration of disubstituted allenes. Access to alkenylboron compounds in high enantiomeric purity.

Jang Hwanjong H Jung Byunghyuck B Hoveyda Amir H AH

Organic letters 20140825 17

Proto-boryl additions to 1,1-disubstituted allenes in the presence of 1.0-5.0 mol % of chiral NHC-Cu complexes, B2(pin)2, and t-BuOH proceed to afford alkenyl-B(pin) products in up to 98% yield, >98:2 site selectivity, and 98:2 er. The enantiomerically enriched alkenylboron products can be converted to otherwise difficult-to-access alkenyl bromides, methyl ketones or carboxylic acids. What's more, the corresponding boronic acids may be used in highly stereoselective NHC-Cu-catalyzed allylic subs ...[more]

PMID: 25153792

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