Chiral lithium binaphtholate effectively catalyzed the enantioselectivealkynylation of ketones using lithium acetylide as an alkynylating agent. This is the first example of the catalytic enantioselective addition of lithium acetylide to carbonyl compounds without the aid of other metal sources.
Enantioselective alkynylation of aldehydes and ketones was accomplished using trimethoxysilylalkynes as alkynylating reagents and lithium 3,3′-diphenylbinaphtholate as a catalyst. Optically active propargylic alcohols were obtained in good to high chemical yields and enantioselectivities. Alkynylation of acetylpyridines afforded biologically active pyridyl propargylic alcohols in good enantioselectivities
Chiral lithium 3,3'-diphenylbinaphtholate successfully catalyzed the alkynylation of ketone with trimethoxysilylalkyne, affording chiral tertiary propargylic alcohols in high chemical yields and high enantioselectivities. The present reaction could be extended to the alkynylation of acetylpyridine, which afforded a biologically active pyridyl propargylic alcohol in good enantioselectivity. (c) 2010 Elsevier Ltd. All rights reserved.
Lithium Binaphtholate-Catalyzed Asymmetric Addition of Lithium Acetylides to Carbonyl Compounds
The asymmetric addition of lithium acetylides to carbonylcompounds in the presence of a chiral lithium binaphtholate catalyst was developed. A procedure involving the slow addition of carbonylcompounds to lithium acetylides improved the enantioselectivity. This reaction afforded diverse chiral secondary and tertiary propargylic alcohols in high yields and with good to high enantioselectivities.