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

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(5H)‐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.