Synthesis of Methyl-substituted 1-Cyclopentene-1-carboxylates and Related Compounds

Publisher Website
Google Scholar
Abstract
The treatment of methyl-substituted 1-chloro-2-oxo-1-cyclohexanecarboxylic esters (7a–e) with anhydrous Na2CO3 in refluxing xylene gave the corresponding methyl-substituted 1-cyclopentene-1-carboxylic esters (1a–e). Several intermediates important in the synthesis of natural products, such as 4,4-dimethyl-1-cyclopentene-1-carbaldehyde (9), 5-methyl-1-cyclopentene-1-carbaldehyde (12), α-(3-methyl-1-cyclopentenyl)propionic acid (16), and ethyl 2-methyl-3-oxo-1-cyclopentene-1-carboxylate (17), have been prepared starting from esters 1e, 1d, 1b, and 1a, respectively.