I₂-Mediated Diversity Oriented Diastereoselective Synthesis of Amino Acid Derived <i>trans</i>-2,5-Disubstituted Morpholines, Piperazines, and Thiomorpholines

Diastereoselective <i>trans</i>-2,5-disubstituted amino acids derived diverse morpholines, piperazines and thiomorpholines were prepared in 30 min-1 h with high yields through iodine<b>-</b>mediated 6-<i>exotrig</i> type cyclization from a single common synthetic intermediate. The displacement of iodine with hydride ion gave a methyl substituent at the 2-position of morpholines which provides an additional opportunity for diversity oriented nucleophilic substitution on the rings as well as incorporation of substituents at the 5-position from amino acids constituents