Efficient Synthesis and Resolution of trans-2-(1-Aryl-1-methylethyl)cyclohexanols; Practical Alternatives to 8-Phenylmenthol

Article abstract of DOI:10.1021/jo00069a031

A short synthesis and resolution of effective chiral auxiliaries of the 8-arylmenthol-type achieved using inexpensive materials, a recyclable lipase, and easily applied procedures that are amenable to large-scale preparation.A variety of isopropylarenes were α-metalated with n-butylithium/potassium tert-pentoxide and treated with cyclohexene oxide to provide racemic trans-2-(1-aryl-1-methylethyl)cyclohexanols 6a-f in fair to high yield.Candida rugosa lipase and lauric acid were used to resolve these racemic alcohols by converting the (-)-enantiomer to its laurateester.The enzymatic resolutions were carried out at 40 deg C and were faster in cyclohexane than in hexanes.The synthesis and resolution of racemic trans-2-(1-methyl-1-phenylethyl)cyclohexanol (6a) were performed on a 1 mol scale in 68 percent overall yield, requiring three steps for (+)-6a and five steps for (-)-6a.