Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture (Angew. Chem. Int. Ed. Engl. 3/1997)
The cover picture shows the molecular structures of two chiral ruthenium complexes that mediate the asymmetric hydrogen transfer between 2-propanol and ketones: on the violet background an amidoruthenium(II) and an amine(hydrido)ruthenium complex (yellow). The examination of the reactivities of the two complexes as well as the kinetics of the rection showed that these two compounds are the only intermediates in this catalytic hydrogen transfer involving secondary alcohols and ketones. In principle this two-component catalytic cycle can continue indefinitely. The structural characteristics and the synthetic utility of these chiral complexes in asymmetric synthesis are discussed by R. Noyori et al. in two communications on pages 285ff. and 288ff.