Synthesis of Chiral Conformationally Fixed Cyclohexanones

Article abstract of DOI:10.1021/jo01300a006

Two syntheses of (R)-(+)-2,2-dimethyl-4-tert-butylcyclohexanone (1) are presented.Related 4-alkylcyclohexanones (intermediates in the syntheses) bear other (potential) conformational anchoring groups.The key steps in the syntheses are the opening of the cyclobutane ring of (+)-3,3-dimethylnopinone (10) by either pyrolysis or reaction with BBr3.The high optical purity of the final compound was determined by analysis of the 19F NMR spectrum of the diastereomeric ester mixture obtained from the reaction of alcohol (+)-14b with (S)-(+)-MTPA chloride