Sequential Claisen and Cope rearrangements: the propenyl ether and acetate of 3-methylhept-6-en-1-yn-3-ol

Abstract

The synthetic potential of a Claisen followed by a Cope rearrangement is illustrated by the reactions of 3-methylhept-6-en-1-yn-3-ol (II). This propargylic alcohol (II) condenses with methyl isopropenyl ether with Claisen rearrangement to give 6-methyldeca-4,5,9-trien-2-one (IV), which isomerises in boiling xylene through the product of Cope rearrangement (V) to 5-isopropylideneocta-trans-3,7-dien-2-one (VI). The acetate (IX) of the alcohol (II) undergoes an analogous series of rearrangements to the allenyl acetate (X) and the dienyl acetate (XII).