Abstract/Summary

A seven-step synthetic route has been developed to access the labile C-3 unsubstituted 5-phenylthiomorpholinone system for the first time. The key step involved the nucleophilic ring opening of Boc-phenylmorpholinone to give the corresponding methyl ester. The sulfur introduction was accomplished through a Mitsunobu reaction to yield a thioacetate, which was then hydrolysed to provide the thiol acid. Cyclization of the thiol acid was achieved using DCC in the presence of DMAP, to give Boc-phenylthiomorpholinone and subsequent deprotection afforded the elusive C-3 unsubstituted 5-phenylthiomorpholinone.