An Efficient Synthesis of 4,4-Dimethyl 5-Methylene-γ-Butyrolactone

Abstract

Cis^1a and -trans^1b Caronaldehyde acids are crucial intermediates for the synthesis of highly potent photostable pyrethroids like deltamethrin^1c and NRDC-182^1d. Recently these intermediates have been obtained by a total synthetic approach from 3, 4-dihydro-4, 4-dimethyl (2H)-pyran-2(one), know as DDP ^1b. The latter is prepared by a zeolite catalysed thermal rearrangement of 4, 4-dimethyl 5-methuylene-γ-butyrolactone (4). The lactone (4) is thus an important intermediate in the total synthtic sequence leading to potent pyrethroids.