A new stereoselective synthesis of trans-chrysanthemic acid [2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylic acid]

Abstract
Base-catalysed interaction of 3-chloro-3-methylbut-1-yne and 3-methylbut-2-en-1 -ol has been shown to produce 2,2-dimethyl-3-(2-methylprop-1-enylidene)cyclopropylmethanol (2). Selective reduction of this allene and subsequent oxidation gave racemic trans-chrysanthemic acid. The method represents a versatile route to many analogues.