Synthesis and Isomerization of the 2-Methyl Enal Fragment of Acyclic Precursors to 9,11-Diene Analogs of Epothilones

Abstract

Yamaguchi esterification of (2Z,5S,6E)-5-(hydroxymethyl)-2,6-dimethyl-7-(2-methyl-1,3-thiazol-4-yl)hepta-2,6-dienal with (2R,5R,6S,7S)-2-(methoxymethoxy)-3,3,5,7-tetramethyl-4-oxo-9-[(1-phenyl-1H-tetrazol-5-yl)sulfonyl-6-[(triethylsilyl)oxy]nonanoic acid afforded the expected acyclic ester. Acid- and base-catalyzed Z,E-isomerization in the 2-methyl enal fragment of acyclic precursors was revealed.