REVISITING OPTICALLY-ACTIVE QUATERNARY DERIVATIVES MADE FROM PROLINOLAS PHASE-TRANSFER CATALYSTS

New non-racemic ammonium salts derived from prolinol have been prepare d which are stereogenic both at N and at C. Absolute configurations re st on X-ray structures for 3c and 7a. The new compounds have been test ed in a number of known enantioselective phase transfer catalytic (PTC ) reactions to gain insight into steric control factors in such proces ses. Only very moderate e.e.s were observed. A SAMP hydrazone related catalyst (7a) reported by other authors was fully characterized. Racem ic reaction products were obtained in two alkylations of diphenylmethy lene benzylimine in the presence of this pure catalyst 7a. Very high e .e.s reported previously by others could not be reproduced. (C) 1998 E lsevier Science Ltd. All rights reserved.