A process for the preparation of a 2,3-dihydro-2-methyl-2,3-dialkyl-7-oxybenzofuran having the formula (I): ##STR1## in which R and R' are the same or different and each represents a lower alkyl group or hydrogen atom, which comprises reacting catechol with an aldehyde having the formula (II): or an alcohol having the formula (III): in a gaseous phase in the presence of a solid acid catalyst. The products are useful as intermediates in the preparation of insecticides.
2-Substituted-1,3-dioxacycloalkanes (also known as acetonides) (such as ##STR1## (4-hydroxy-2,2-dimethyl-1,3-benzodioxole)) are prepared by reacting a diol (such as 1,2,3-trihydroxybenzene) and a diunsaturated ether (such as diisopropenyl ether). The reaction is exothermic and produces a ketone as the only by-product. The invention has utility in hydroxyl moiety "protection" and in pesticide synthesis.
