Abstract
3-Methyl-4-octanolidea, γ-lactone known as a constituent of alcoholic beverages as Quercus lactone or Whisky lactone was synthesized from readily available starting materials. The synthetic route is shown in Scheme-1. The Michael reaction of nitropentane (1a) with methyl crotonate (2a) catalyzed by DBU in DMSO gave methyl 3-methyl-4-nitrooctanoate (3a) in 80% yield. Methyl 3-methyl-4-oxooctanoate (4a) was obtained from (3a) by Nef reaction with the electochemical oxidation in 88% yield. Reduction of (4a) with sodium borohydride gave a mixture of trans-, and cis-Quercus lactone (5a), and (5b).
Similarly, trans-3-methyl-4-nonanolide (6a), reported as a constituent of cognac, was prepared from methyl 3-methyl-4-nitrononanoate (3a).
