Regioselective synthesis of 5-ethoxycarbonyl-, 5-acetyl- and 5-trifluoroacetyl-6-trifluoromethylsalicylates by one-pot cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 3-alkoxy-2-alken-l-ones

摘要

5-Ethoxycarbonyl-, 5-trifluoroacetyl-, and 5-acetyl-6-trifluoromethylsalicylates were prepared by one-pot cyclizations of l,3-bis(triniethylsilyloxy)-1,3-butadienes with 3-alkoxy-2-alken-1-ones. The reactions proceeded with very good regioselectivity by conjugate addition of the terminal carbon atom of the diene to the enone and subsequent cycHzation. The cychzation proceeded in most cases via the trifluoroacetyl group.