Processes for preparing 5,5-dimethyl-2-oxo-3-cyclopentene-1-carboxylate compounds and 3,5,5-trimethyl-2-oxo-3-cyclopentene-1-carboxylate compounds from 3,3-dimethyl-1-butene-1,4-dicarboxylate compounds and 1,3,3-trimethyl-1-butene-1,4-dicarboxylate compounds, and 1,3,3-trimethyl-1-butene-1,4-dicarboxylate compounds

Abstract

The present invention provides a process for preparing a compound of the following general formula (2): wherein Rrepresents a monovalent hydrocarbon group having 1 to 10 carbon atoms, and Rrepresents a hydrogen atom or a methyl group, the process comprising: subjecting a compound of the following general formula (1): wherein Rand Rrepresent, independently of each other, a monovalent hydrocarbon group having 1 to 10 carbon atoms, Rrepresents a hydrogen atom or a methyl group, and the wavy bond represents an E-configuration, a Z-configuration, or a mixture thereof, to a Dieckmann condensation in the presence of base to form the compound (2).