Sulfinamides as Highly Effective Amine Protecting Groups and Their Use in the Conversion of Amino Alcohols into Morpholines

Abstract 1,2‐Amino alcohols have been converted into morpholines by using sulfinamides as temporary protecting/activating groups on the amine. We have developed a procedure for the selective synthesis of monoprotected N‐sulfinyl amino alcohols through a double sulfinylation/hydrolysis strategy. Following the reaction of the sulfinamides with bromoethyldiphenylsulfonium triflate, protected morpholines were obtained in high yields. Subsequent treatment with HCl liberated the morpholine hydrochloride salts. The usefulness of this high yielding and efficient methodology has been demonstrated in the formal synthesis of the antidepressant drug (S,S)‐reboxetine.