Regulatory nature of beta-cyclodextrin in selective ring-opening during reduction of styrene oxide

The cleavage of styrene oxide by different reagents like Raney nickel, pall adium-carbon and sodium borohydride in the presence of beta-cyclodextrin an d its derivatives like beta-CD-epichlorohydrin (beta-CD-polymer) and heptak is-2,6-di-O-methyl-beta-cyclodextrin (DM beta-CD) showed distribution in fo rmation of ethylbenzene, 1-phenylethanol and 2-phenylethanol. Formation of deoxygenated products like styrene and ethylbenzene were suppressed by beta -CD and its derivatives under hydrogenation over Raney nickel favouring inc rease in proportion of 2-phenylethanol. beta-CD and its derivatives regulat ed increase in formation of 1-phenylethanol under reduction by Pd-C and NaB H4. Observed selectivities have been correlated to arise directly from the disposition adopted by styrene oxide inside the beta-CD cavity, the nature and manner of which has been arrived at from the spectroscopic studies (UV and NMR) of inclusion. (C) 1999 Elsevier Science B.V. All rights reserved.