ChemInform Abstract: A Rearrangement Route to Fenvaleric Acid.

Abstract

(±)-Fenvaleric acid 2, the key intermediate for the preparation of the pesticide esfenvalerate 1, was prepared by a novel sequence which first involves the Henry reaction of 2-methyl-1-nitropropane and 4-chlorobenzaldehyde. The nitroaldol reaction provided nitroalcohol 5 which was then reduced to the corresponding aminoalcohol 6. Submission of 6 to an aminopinacol rearrangement promoted by nitrous acid deamination then afforded aldehyde 8 through a 1,2-aryl shift. The product fenvaleric aldehyde 8 was then converted to the title compound 2 by a modified Jones oxidation.