Michael and Substitution Reactions of Bicyclic Tetronic, Tetramic and Thiotetronic Esters.

Abstract The 1,4-addition of several hetero- and carbon nucleophiles to the bicyclic structures 1, 2, 3 and 17 are reported along with the conversion of the resultant adducts to substituted tetronic, tetramic, and thiotetronic acids as well as the formation of substituted butenolides; a novel reaction mechanism has been observed for the iodotrimethylsilane (TMSI) or acetic anhydride/magnesium bromide mediated furan ring opening reaction of the bicyclic tetronate 1.