<i>p</i>-Menthane-3-carboxaldehyde: A Useful Chiral Auxiliary for the Synthesis of Chiral Quaternary Carbons of High Enantiomeric Purity

Abstract

(+)- or (-)-p-Menthane-3-carboxaldehyde is made in two easy steps from (+)- or (-)-menthone, respectively. This auxiliary allows for the synthesis of carbonyl compounds bearing a alpha-chiral quaternary carbon. The flexibility, efficiency, and ease of use of the method are demonstrated in a series of examples, which include the total synthesis of (+)-cuparenone as well as a partial synthesis of (-)-cassiol.