The xanthate route to lactams

Abstract

Convergent routes to various classes of lactams exploiting the unique radical chemistry of xanthates are described. Emphasis is placed on reactions leading to lactams by direct radical cyclization, by intermolecular additions to alkenes followed by ring closure, and by radical additions to alkenes furnishing amino esters and amino acids precursors that can be converted into lactams by ionic condensations. The possibility of modifying existing lactam structures is briefly discussed. Four-, five-, six-, seven- and, more rarely, eight-membered lactams can be constructed, including five-, six-, seven-membered lactams fused to aromatic and heteroaromatic rings. The latter are exemplified by oxindoles, azaoxindoles, tetrahydroquinolones, tetrahydroisoquinolones tetrahydroazaquinolones, tetrahydrobenazepinones, and tetrahydropyridoazepinones.