Pentacarbonyl(1-acyloxyalkylidene)chromium(0) complexes, formed in situ by reaction of the corresponding tetramethylammonium pentacarbonyl(1-oxoalkyl)chromate(1−) salts with carboxylic acid halides, affords enol esters in moderate to good yields. In all cases examined, the Z-enol ester was obtained as the major or exclusive isomer. Addition of 1 equiv of pyridine to the reaction mixture substantially improved the Z/E ratio and, in most cases, increased the chemical yield.

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reactions of organo-metal compounds reactions of organo-metal compounds O 0350 -065Thermal Decomposition of Pentacarbonyl(1acyloxyalkylidene)chromium(0) Complexes: Formation of Z-Enol Esters.-A novel synthesis of enol esters in moderate to good yields by reaction of pentacarbonyl Cr(0) complexes (formed in situ from NMe + 4 chromate salts) with carboxylic acid halides is presented. The Z-enol ester is obtained as the major or exclusive isomer. The addition of 1 equiv. Py improves the Z/E ratio and, in most cases, increases the yields. -(SOEDERBERG, B. C.; LIU, J.; BALL, T. W.; TURBEVILLE, M. J.; J.