The
regioselective trifluoromethylthiolation of indole derivatives
was achieved under reductive conditions with trifluoromethanesulfonyl
chloride as the readily available source of electrophilic SCF3 and a phosphine as the reducing agent. It is a straightforward
process free from any metal and also applicable for the trifluoromethylthiolation
of other azaarenes, enamines, and enoxysilanes.
The palladium-catalyzed asymmetric decarboxylative allylic alkylation of trifluoromethoxy allyl enol carbonates afforded enantioenriched α-trifluoromethoxy allyl ketones that feature a tetrasubstituted α-stereogenic center in excellent yield and high enantioselectivity. The method was further extended to the asymmetric synthesis of α-difluoromethoxy and α-methoxy allyl ketones, which proceeded under similar catalytic conditions.
The synthesis of chiral, nonracemic difluoromethylthio (SCF 2 H) compounds that contain a tetrasubstituted stereogenic center is reported. Racemic α-SCF 2 H-β-ketoallylesters 5 were initially prepared by an electrophilic difluoromethylthiolation of β-ketoallylesters 6, followed by a Pd-catalyzed Tsuji decarboxylative asymmetric allylic alkylation (DAAA) to provide a wide variety of chiral, nonracemic α-allyl-α-SCF 2 H-ketones (4) with high enantiopurity. This strategy can be extended to the enantioselective synthesis of chiral, nonracemic α-allyl-α-trifluoromethylthio(SCF 3 )-ketones (7).
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