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

摘要

The present invention provides a process for preparing a compound of the following general formula (2): wherein R1 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, and R3 represents a hydrogen atom or a methyl group, the process comprising: subjecting a compound of the following general formula (1): wherein R1 and R2 represent, independently of each other, a monovalent hydrocarbon group having 1 to 10 carbon atoms, R3 represents 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).