Michael Additions Involving Amino Acid Esters with Alkenyl N-Heterocycles

Michael addition has been achieved with a variety of amino acid esters and 2- or 4-vinylpyridine. Similar reactions were accomplished with an alkenyl-substituted pyrimidine, pyrazine, thiazole, quinoxaline, benzoxazole, and quinolone. In reactions at a prochiral center, modest diastereoselectivities were observed with the formation of the new stereogenic carbon. NMR experiments indicate that the addition reaction is reversible under acidic conditions.