Three-component Ag-catalyzed enantioselective vinylogous mannich and aza-diels - Alder reactions with alkyl-substituted aldehydes

Hiroki Mandai, Kyoko Mandai, Marc L. Snapper, Amir H. Hoveyda

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112 Citations (Scopus)

Abstract

Efficient protocols for three-component catalytic enantioselective vinylogous Mannich (VM) reactions of alkyl-substituted aldimines (including those bearing heteroatom-containing substituents) and readily available siloxyfurans are presented. High efficiency and stereoselectivity is achieved through the use of o-thiomethyl-p-methoxyaniline-derived aldimines. Reactions, performed under an atmosphere of air and in undistilled THF, can be promoted in the presence of as little as 1 mol % of easily accessible amino acid-based chiral ligands and commercially available AgOAc. The desired products are obtained in 44 to 92% yield, and in up to >98:<2 diastereomer and >99:<1 enantiomer ratio (>98% ee). Removal of the N-activating group is performed through a one-vessel oxidation/hydrolysis operation, which proceeds via a stable aza-quinone (characterized by X-ray crystallography). Evidence is presented indicating that reactions with chiral nonracemic aldehydes are subject to catalyst control: both substrate enantiomers react to afford the desired product diastereomers in high stereoselectivity. Aryl- and alkynyl-substituted o-thiomethyl-p-methoxyaniline-derived aldimines undergo Ag-catalyzed enantioselective VM reactions more efficiently and with higher selectivity than the corresponding o-anisidyl substrates. Additionally, Ag-catalyzed aza-Diels-Alder reactions of the alkyl-substituted aldimines bearing the structurally modified N-aryl unit afford enantiomerically enriched (up to 95% ee) products in up to 88% yield.

Original languageEnglish
Pages (from-to)17961-17969
Number of pages9
JournalJournal of the American Chemical Society
Volume130
Issue number52
DOIs
Publication statusPublished - Dec 31 2008

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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