Versatile one-pot synthesis of benzo-fused thiacycles by copper catalysis

Abstract

A novel, one-pot synthesis of structurally diverse benzo-fused thiacycles via a Cu-catalysed intermolecular C–S coupling/cyclisation tandem process, employing the same catalytic system, has been developed. Thus, 3,4-dihydro-2H-benzo[e][1,3]thiazines and 4H-benzo[e][1,3]thiazines were selectively obtained by this one-pot tandem process from (2-iodophenyl)methanamine and aldehydes or 1-(azidomethyl)-2-iodobenzene, respectively. These reactions proceeded in toluene at 100 °C with potassium thioacetate, thiobenzoate or ethyl xanthogenate in moderate to good isolated yields. The first one avoids the imine isolation step. A similar approach to benzo[b]thiophene derivatives from 2-(2-iodophenyl)acetonitrile was also developed.