CeCl3·7H2O/AcCl-catalyzed Prins–Ritter reaction sequence: a novel synthesis of 4-amido tetrahydropyran derivatives

Homoallylic alcohols, carbonyl compounds and nitriles undergo a smooth tandem Prins–Ritter type cyclization in the presence of CeCl3·7H2O/AcCl at ambient temperature to produce 4-amido tetrahydropyrans in high yields with all cis-selectivity. Spirocyclic 4-amido tetrahydropyrans are obtained in the case of cyclic ketones.