New chiral auxiliaries, alcohols syn-lla,e and anti-12a,e, were readily synthesized in a stereoselective manner from (-)-fl-pinene. Their stereochemical determinations have been made on the basis of nOe experiments. (~) 1997 Elsevier Science Ltd. All rights reserved.
A survey of recent chemical literature reveals an explosion of interest in the development of new chiral auxiliaries to accomplish synthetic transformations with a high degree of asymmetric induction. The landmark in this field was reported by Corey in 1975 with the synthesis of (+)-8-phenylmenthol 1 from (-)-pulegone and its successful application to a highly diastereoselective Diels-Alder reaction of the corresponding acrylate.l Its enantiomer, (-)-8-phenylmenthol 2, 2 firstly prepared by Oppolzer from naturally occurring (+)-pulegone, has become one of the most powerful and widely used chiral auxiliaries in organic synthesis. Among the numerous chiral auxiliaries reported during the past two decades, trans-2-phenylcyclohexanol 33 as well as trans-2-arylcyclohexanols 4, 4 trans-2-(1-methyl 1-arylethyl)cyclohexanols 55 and 2,2-diphenylcyclopentanol 74a,6 emerged as powerful simplified equivalents to (-)-8-phenylmenthol 2 or 8-arylmenthols 6. 7