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  • Cinchona alkaloid-catalyzed asymmetric trifluoromethylation of alkynyl ketones with trimethylsilyl trifluoromethane.

Cinchona alkaloid-catalyzed asymmetric trifluoromethylation of alkynyl ketones with trimethylsilyl trifluoromethane.

Organic letters (2010-10-20)
Hiroyuki Kawai, Kentaro Tachi, Etsuko Tokunaga, Motoo Shiro, Norio Shibata
ABSTRACT

The first catalytic enantioselective trifluoromethylation of alkynyl ketones 1 with (trifluoromethyl)trimethylsilane is disclosed by an operationally simple procedure, based on the combination of ammonium bromide of bis-cinchona alkaloids with Me(4)NF to afford trifluoromethyl-substituted tertiary propargyl alcohols (up to 96% ee), which are the important chiral building blocks for pharmaceuticals. Biologically attractive aryl heteroaryl trifluoromethyl carbinols were also synthesized.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ammonium bromide, 99.999% trace metals basis
Sigma-Aldrich
Ammonium bromide, ACS reagent, ≥99.0%
Sigma-Aldrich
Ammonium bromide, ≥99.99% trace metals basis