CsF-catalyzed nucleophilic trifluoromethylation of trans-enones with trimethyl(trifluoromethyl)silane: A facile synthesis of trans-alpha-trifluoromethyl allylic alcohols

[GRAPHICS] Reactions of trans-enones, R-C=C-COR' (R = Ph, Me, -C=CH-CH=C-S; R' = Ph, M e, Pt, CFB) (la-e), with TMS-CF3 in the presence of catalytic amounts of ce sium fluoride (CsF) in ethylene glycol dimethyl ether led to the formation of the corresponding trans-alpha-trifluoromethyl silyl ethers, R-C=C-C(OSiM e3)(CF3)R' (R = Ph, Me, -C=CH-CH=C-S; R' = Ph, Me, Pt, CFB) (2a-e), in esse ntially quantitative yield. On hydrolysis with aqueous HCl, the correspondi ng trans-alpha-trifluaromethyl allylic alcohols, R-C=C-C(OH)(CF3)R' (R = Ph , Me, -C=CH-CH=C-S; R' = Ph, Me, Et, CF3) (3a-e), were formed in >90% isola ted yield. Under similar reaction conditions, 2-cyclohexen-1-one (1f) also gave trifluoromethyl allylic alcohols (3f) in 92% yield. The intermediates (2a-f) and products (3a-f) are liquids and were characterized by IR, H-1, ( 19)f and C-13 NMR, MS, and high-resolution mass spectroscopy (HRMS).