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Diastereoselective Additions of (R)-( + )-Methyl p-Tolyl Sulfoxide Anion to Imines. Asymmetric Synthesis of (R)-( + )-Tetrahydropalmatine1

Journal Article


Abstract


  • The addition of the lithium carbanion of methyl phenyl sulfoxide and (R)-(+)-methyl p-tolyl sulfoxide to imines having at least one aryl substituent, under kinetically controlled conditions, gives /3-amino sulfoxides with good to modest diastereoselection. Under equilibrium controlled condition poor product diastereoselection results. The addition of these anions to 3,4-dihydro-6,7-dimethoxyisoquinoline is unique in that the most favorable product diastereoselection (92:8) is observed under equilibrium controlled conditions. Deuteration experiments suggest that equilibration occurs via a (8-amino a-lithio sulfinyl carbanion through a retro-Michael addition then Michael addition reaction sequence. This methodology allows for the construction of (R)-(+)-tetrahydropalmatine in four efficient synthetic steps. © 1990, American Chemical Society. All rights reserved.

Publication Date


  • 1990

Citation


  • Pyne, S. G., & Dikic, B. (1990). Diastereoselective Additions of (R)-( + )-Methyl p-Tolyl Sulfoxide Anion to Imines. Asymmetric Synthesis of (R)-( + )-Tetrahydropalmatine1. Journal of Organic Chemistry, 55(6), 1932-1936. doi:10.1021/jo00293a045

Scopus Eid


  • 2-s2.0-33751552929

Web Of Science Accession Number


Start Page


  • 1932

End Page


  • 1936

Volume


  • 55

Issue


  • 6

Abstract


  • The addition of the lithium carbanion of methyl phenyl sulfoxide and (R)-(+)-methyl p-tolyl sulfoxide to imines having at least one aryl substituent, under kinetically controlled conditions, gives /3-amino sulfoxides with good to modest diastereoselection. Under equilibrium controlled condition poor product diastereoselection results. The addition of these anions to 3,4-dihydro-6,7-dimethoxyisoquinoline is unique in that the most favorable product diastereoselection (92:8) is observed under equilibrium controlled conditions. Deuteration experiments suggest that equilibration occurs via a (8-amino a-lithio sulfinyl carbanion through a retro-Michael addition then Michael addition reaction sequence. This methodology allows for the construction of (R)-(+)-tetrahydropalmatine in four efficient synthetic steps. © 1990, American Chemical Society. All rights reserved.

Publication Date


  • 1990

Citation


  • Pyne, S. G., & Dikic, B. (1990). Diastereoselective Additions of (R)-( + )-Methyl p-Tolyl Sulfoxide Anion to Imines. Asymmetric Synthesis of (R)-( + )-Tetrahydropalmatine1. Journal of Organic Chemistry, 55(6), 1932-1936. doi:10.1021/jo00293a045

Scopus Eid


  • 2-s2.0-33751552929

Web Of Science Accession Number


Start Page


  • 1932

End Page


  • 1936

Volume


  • 55

Issue


  • 6