Enzyme Reactions in Apolar Solvent. 5. The Effect of Adjacent Unsaturation on the PPL-Catalyzed Kinetic Resolution of Secondary Alcohols

Article abstract of DOI:10.1021/jo00037a049

The effect of adjacent unsaturation on the enzyme-catalyzed kinetic resolution of secondary alcohols is studied for a series of allylic, homoallylic, propargylic, homopropargylic, and phenyl-substituted 2-alkanols, using porcine pancreatic lipase (PPL) in anhydrous Et2O.Excellent enantioselectivity (high E value) was observed for α-phenethyl alcohol (3), propargylic alcohols (8 and 11), and (E)-allylic alcohols (9 and 12), but (Z)-allylic alcohols (10 and 13) showed poor selectivity.Enantioselectivity was also low for both (E)- and (Z)-homoallylic alcohols (15 and 16), homopropargylic alcohol (14), 1-phenyl-2-propanol (6), and 4-phenyl- 2-butanol (7).The enhanced enantioselectivity observed for (E)-allylic alcohols was exploited in the synthesis of the enantiomers of both components of the aggregation pheromone of the lesser grain borer, Rhyzopertha dominica (F.).The magnitude of the enantiomeric ratio (E value) can be dramatically affected by the accuracy of the values of ee_s and ee_p used in the calculation, especially when E is large.Variation in the value of E with the optical purity of the chiral derivatizing agent used to determine ee_s and ee_p is illustrated.