Diastereoselectivity in the Reduction of α‐Oxy‐ and α‐Amino‐Substituted Acyclic Ketones by Polymethylhydrosiloxane.

Abstract

Diastereoselective syntheses Diastereoselective syntheses O 0031Diastereoselectivity in the Reduction of α-Oxyand α-Amino-Substituted Acyclic Ketones by Polymethylhydrosiloxane. -High syn-selectivity is observed in the reduction of α-alkoxy, α-acyloxy, and α-dialkylamino ketones by PMHS in the presence of catalytic amounts of fluoride ions. No epimerization occurs under these conditions. The reduction of α-monoalkylamino ketone (III) proceeds in anti-selective manner with moderate selectivity. The observed diastereoselectivities are explained based on Felkin-Anh and Cram-chelate models. -(NADKARNI*, D.; HALLISSEY, J.; MOJICA, C.; J. Org. Chem. 68 (2003) 2, 594-596; Process Dev. Lab., Pfizer Global Manuf., Groton, CT 06340, USA; Eng.) -Klein 22-031

Highly Recyclable Fluoride for Enhanced Cascade Hydrosilylation–Cyclization of Levulinates to γ-Valerolactone at Low Temperatures

“…7−10 Unfortunatedly, some practical drawbacks like poor catalyst reusability and the requirement of proton species or extra hydrolysis steps for the dissociation of Si−X (X = O, N, and S) bonds to liberate products are always encountered, especially for the selective hydrogenation of carbonyl compounds. 11,12 To the best of our knowledge, no effective approach has been reported to simplify the postprocess and further in situ couple the hydrosilylation with other reactions.…”