Diastereoselectivity in the reduction of α-oxy- and α-amino-substituted acyclic ketones by polymethylhydrosiloxane

Diastereoselectivity in the reduction of α-alkoxy-, α-acyloxy-, and a-alkylamino-substituted ketones with polymethylhydrosiloxane (PMHS) in the presence of fluoride ion catalysis was investigated. High syn-selectivity was observed in the reduction of a-alkoxy, α-acyloxy, and α-dialkylamino ketones. Reduction of α-monoalkylamino ketone proceeded in anti-selective manner with moderate selectivity. The observed selectivity is explained based on Felkin-Anh and Cram-chelate models.