A NEW ROUTE TO SUBSTITUTED DIHYDROPYRANS

Deprotonation and subsequent alkylation of ,4-dihydro-6-(para-toluenes ulfonylmethyl)-2H-pyran gives monoalkylated products in good yields, w ith excellent a selectivity. The alkylation succeeds not only for reac tive haloalkanes, but also for simple primary and secondary alkyl brom ides. Desulfonylation with sodium amalgam provides a new and simple ro ute to substituted dihydropyrans.