Synthesis of <i>cis</i> and <i>trans</i> Whisky and Cognac lactones by the regiocontrolled alkylation of 2‐(trimethylsiloxy)furan

Abstract

Abstract The racemic cis ‐ and trans ‐5‐butyltetrahydro‐4‐methylfuran‐2‐ones ( = whisky lactones) and their higher homologues tetrahydro‐4‐methyl‐5‐pentylfuran‐2‐ones ( = cognac lactones) have been prepared in 2–3 steps from 2‐(trimethylsiloxy)furan. Regioselective alkylation of the latter afforded the 5‐butyl‐ and 5‐pentylfuran‐2(5 H )‐ones which served as precursors for the stereocontrolled construction of either diastereoisomer of the beverage lactones. The structure and tautomerization of the diazomethane adducts of these 5‐alkylfuran‐2(5H)‐ones are also described.