Cleavage of 2-methyl-5,6-dihydro-2h-pyrane by acid halides

The reaction of 2-methyl-5,6-dihydro-2H-pyrane with a number of acid halides in which the ring is cleaved is accompanied by an allylic rearrangement. The halogen atom in the isomers is replaced in the usual way by nucleophilic reagents, but aqueous alkali causes in addition the formation of 1,3,5-hexatriene and to a lesser extent recyclization to dihydropyrane.Translated from Khimiya Geterotsikhicheskikh Soedinenii, No. 12, pp. 1600–1602, December, 1984.