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■ Enantioselective Synthesis of 2,4,5-Trisubstituted Tetrahydropyrans via Peptide-Catalyzed Michael Addition Followed by Kishi’s Reductive Cyclization

Atsushi Ueda,* Mei Higuchi, Tomohiro Umeno, and Masakazu Tanaka*

*Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan

Abstract

An enantioselective synthesis of 2,4,5-trisubstituted tetrahydropyrans has been achieved in four steps from α,β-unsaturated ketones and dimethyl malonate by peptide-catalyzed asymmetric Michael addition and diastereoselective construction of tetrahydropyran rings by Kishi’s reductive cyclization as key steps. A variety of α,β-unsaturated ketones were converted to the 1,4-products with high enantioselectivities (83–98% ee).