Stereoselective Synthesis of cis ‐ p ‐Menth‐8‐ene‐1,7‐diol, cis ‐ p ‐Menthane‐1,7‐diol, and cis ‐ p ‐Menthane‐1,7,8‐triol

The natural products cis ‐ p ‐menthane‐1,7‐diol ( cis ‐ IV ), cis ‐ p ‐menth‐8‐ene‐1,7‐diol ( cis ‐ I ) and cis ‐ p ‐menthane‐1,7,8‐triol ( cis ‐ II ) are obtained starting from the corresponding cis ‐cyanohydrins, cis ‐ 2 and cis ‐ 7 , respectively, by chemical transformation of the cyano into the hydroxymethyl group. The key step of the synthesis is the very high cis ‐selectivity (≥ 96 %) of the MeHNL‐catalyzed HCN addition to 4‐alkylcyclohexanones. From 4‐isopropylcyclohexanone ( 1 ) the cyanohydrin cis ‐ 2 and from 4‐(1‐methylvinyl)cyclohexanone ( 6 ) the cyanohydrin cis ‐ 7 result almost quantitatively. Regioselective hydroxylation of cis ‐ I affords the triol cis ‐ II . X‐ray crystal structure determinations of the final products confirm their cis ‐configuration.