Iodoarene-Mediated Cyclization of N-Methoxy-2-arylethanesulfonamides with Oxone

Iodoarene-mediated cyclization of N-methoxy-2-arylethanesulfonamides with Oxone ® was carried out to form the corresponding N-methoxy-3,4-dihydro-2,1-benzothiazine-2,2-dioxides in moderate to good yields in acetonitrile.In this reaction, reactive hypervalent iodine species, i.e., [(hydroxy)(tosyloxy)iodo]arenes, were formed in situ and reacted with N-methoxy-2-arylethanesulfonamides to form the corresponding N-methoxy-3,4-dihydro-2,1-benzothiazine-2,2-dioxides in an electrophilic manner on the aromatic ring.Ion-supported PhI could be also used for the same cyclization of N-methoxy-2-arylethanesulfonamides with Oxone ® to provide N-methoxy-3,4-dihydro-2,1-benzothiazine-2,2-dioxides in good to moderte yields.However, ion-supported PhI could not be reused for the same reaction.The same iodoarene-mediated cyclization of N-methoxy-3phenylpropanamide and N-methoxy-4-phenylbutanamide with Oxone ® was also carried out to form the corresponding N-methoxybenzolactams in moderate yields.