Synthetic studies on cembranolides. Stereoselective synthesis of epoxy ester intermediates

…, MJ Coghlan, M Watanabe

Index: Marshall, James A.; Coghlan, Michael J.; Watanabe, Masataka Journal of Organic Chemistry, 1984 , vol. 49, p. 747 - 753

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Citation Number: 12

Abstract

A stereorational synthesis of the epimeric epoxy esters 17 and 21 from methacrolein is described. The route employs two key stereodirected steps. The first, copper-catalyzed addition of vinylmagnesium bromide to conjugated lactone 7, gives the trans product 8. The second, iodolactonization of the derived diesters 11 or 12, leads to the trans lactones 16b or 16c. Basic methanolysis then gives the epoxides 17b or 17c. The latter is converted to the ...