THE ENANTIOSELECTIVE INFLUENCE ON THE HYD ROLYSIS OF NITROARYLESTERS OF 2-METHOXY-2-PHENYLACETIC ACIDS BY CYCLODEXTRINS

2-Nitrophenyl-, 4-nitrophenyl- and 2,4-dinitrophenylesters of the (R)- , (S)- and (R/S)-2-methoxy-2-phenylacetic acid (MPE) are produced to s tudy the catalytic influence of cyclodextrins (CD) on the hydrolysis o f chiral esters. gamma-CD demonstrates a higher effect than alpha-CD, which does not decrease by increasing the pH value. The stability cons tants of the complexes are not very different. The cleavage of the (S) -enantiomers by alpha-, hydroxypropyl (HP)-beta and gamma-CD is lower than that of the (R)-enantiomers whereby the extent of difference depe nds on the kind of the substrate. Most distinctly one can recognize th e reation of MPE-4-nitrophenylester to HP-beta-CD. Obviously the inter action of the D-glucose unit of the CD with the (S)-substrate leads to a diastereomer which is energetically discriminated (R/S) against the (R)-substrate resulting in an inhibition of (R) hydrolysis. Because t he same especially appears with HP-beta-CD it is demonstrated that the enantioselectivity of CD demands an optimum of adaptability of the su bstrate existing in small limits only.