A Practical and Efficient Synthesis of <i>p</i>-Menthane-3,8-diols

Abstract

The diastereomeric repellents of p-menthane-3,8-diol were produced from citronellal by treatment with 0.25% sulfuric acid at 50 °C for 11 h to give 97.9% conversion and 92.3% selectivity and citronellal acetal by-products with only 2.7%. The crude products were crystallized from n-heptane at −50 °C for 20 h to give p-menthane-3,8-diols in 80% yield and high purity. The stereochemistry of the citronellal acetal by-products was determined by 2D NMR and NOE.