title: Highly stereoselective synthesis of 2,6-cis-substituted tetrahydropyrans using a one-pot sequential catalysis.
abstract: A catalytic highly diastereo- and enantioselective synthesis of 2,6-cis-substituted tetrahydropyrans was realized using a one-pot sequential catalysis involving Henry and oxa-Michael reactions. The nitroaldol products obtained in a highly enantioselective copper(II)-catalyzed Henry reaction between nitromethane and 7-oxo-hept-5-enals were subsequently treated with a catalytic amount of camphorsulfonic acid (CSA) to give the desired tetrahydropyran derivatives in excellent yields, diastereoselectivities (dr >99:1), and enantioselectivities (ee = 98-99%). The reaction can also be used for the high stereoselective synthesis of a cis-2,6-disubstituted morpholine.
authors.affiliation: Department of Chemistry, University of Texas at San Antonio , One UTSA Circle, San Antonio, Texas 78249-0698, United States.
authors.forename: Qipu
authors.initials: Q
authors.lastname: Dai
authors.forename: Nirmal K
authors.initials: NK
authors.lastname: Rana
authors.forename: John Cong-Gui
authors.initials: JC
authors.lastname: Zhao