A Study of Rearrangement of Some 1,3-Dimethoxyalkan-2-ones.

1,3-Dialkoxyacetones, 1-alkyl- and 1-(substituted phenyl)-, 1-alkanoyl-1,3-dimethoxyacetones, and methyl 2,4-dimethoxyacetoacetate were shown to undergo acid-catalysed rearrangement to give respectively methylglyoxal dialkyl acetals, 3-substituted methylglyoxal dimethyl acetals, 5-alkyl-3-methoxy- and 4,5-dimethoxyfuran-2(5H)-ones. 1-(Substituted aroyl)-1,3-dimethoxyacetones underwent only scission to give substituted ω-methoxyacetophenones. Methyl 2-alkyl-2,4-dimethoxyacetoacetates, 3- and 1-methoxy-, and 1,5-dimethoxypentane-2,4-diones were not affected by similar acid treatment except for the fact that they suffered some limited C–C bond scissions. Implications related to rearrangement mechanisms are discussed.