Water-Soluble Palladium Complex of N '-(pyridin-2-yl)propane-1,3-diamine modified beta-Cyclodextrin: An efficient Catalyst for Transfer Hydrogenation of Carbonyl Compounds

Synthesis of a water-soluble Pd(II) complex of N'-(pyridin-2-yl)propane-1,3-diamine modified beta-cyclodextrin (Pd(II)@PyPDA:beta-CD) is reported. The synthesized Pd(II)@PyPDA:beta-CD, characterized by FT-IR, NMR, mass, UV-vis spectroscopies and molecular modeling studies, is used as a homogeneous, ecofriendly and reusable catalyst under mild reaction conditions for transfer hydrogenation of aromatic ketones to secondary alcohols using isopropyl alcohol as a green reducing agent. This homogeneous catalyst is reused five times with only a small decrease in its catalytic activity. The presence of a chiral cavity in cyclodextrin, is found to facilitate significant chiral induction, evident from preliminary chiral HPLC studies. A plausible mechanism for hydrogenation is proposed. Other significant advantages of the present catalyst, namely, simple preparation, stability, substrate selectivity, easy recovery, and reusability highlight its potential utility in other reactions and also in industrial applications.