Bismuth(III) triflate is found to be an effective Lewis acid in catalyzing a three-component reaction of homoallylic alcohol, carbonyl compound, and nitrile at ambient temperature via the Prins–Ritter sequence to furnish 4-amidotetrahydropyrans in high yields, all with cis selectivity. Spirocyclic 4-amidotetrahydropyrans are obtained in case of cyclic ketones.Key words: Prins cyclization, bismuth(III) triflate, homoallyl alcohol, 4-amidotetrahydropyrans.
A convenient and diastereoselective one-pot synthesis of cis-4-amidotetrahydropyrans is described. This simple protocol involves Prins cyclization of homoallylic alcohol and aldehydes, followed by Ritter reaction of acetonitrile leading to the formation of cis-4-acetamidopyrans in good yields.