Ion-supported PhI-catalyzed cyclization of N-methoxy-2-arylethanesulfonamides with mCPBA

The ion-supported PhI-catalyzed cyclization of N-methoxy-2-arylethanesulfonamides with mCPBA was carried out to form the corresponding N-methoxy-3,4-dihydro-2,1-benzothiazine-2,2-dioxides in moderate to good yields in 2,2,2-trifluoroethanol. Here, reactive hypervalent iodine compounds, that is, ion-supported [(hydroxy)(tosyloxy)iodo]benzenes, 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. Moreover, ion-supported Phi could be efficiently reused to provide the products in good yields. The same ion-supported PhI-catalyzed cyclization of N-methoxy-3-phenylpropionamide and N-methoxy-4-phenylbutyramide with mCPBA was carried out to form the corresponding N-methoxy benzolactams in moderate yields in 2,2,2-trifluoroethanol. (C) 2009 Elsevier Ltd. All rights reserved.