Highly Enantioselective Transfer Hydrogenation of Aromatic Ketones

手性芳香醇在制药工业上有重要的应用,因而利用芳香酮的对映选择性氢化制备相应的手性醇已引起人们极大关注.近10年来,用手性金属配合物为催化剂,利用种种有机物作氢源,实现芳香酮的不对称氢转移氢化取得了很大进展.但这些反应过程的催化活性仍然较低,底物酮与催化剂Enantioselective reduction of prochiral ketones with 2-propanol or formic acid catalyzed by chiral metal complexes has been developed as a synthetic method complementary to asymmetric hydrogenation in the past decade. However, these processes are necessary to be improved for practical use in organic synthesis because of low catalytic activity and insufficient enantioselectivity. In this paper, we wish to report an excellent catalytic system generated in situ from iridium complex IrCl(Ph3P)3 and chiral tetradentate di-aminodiphosphine ligand for asymmetric transfer hydrogenation of various aromatic ketones. For isobuty-rophenone transfer hydrogenation, the corresponding optically active alcohol was obtained in 93% yield and with up to 99% e. e. after 5 h at 28℃. Propiophenone was a better substrate with respect to catalytic activity and enantioselectivity in the presence of base as a co-catalyst. The conversion of propiophenone reached 95. 8% and the turnover number as high as 3 193 h-1. These results will provide a useful index for further designing practical chiral catalytic systems.国家自然科学基金(批准号:20073034,20171037);; 福建省科技厅重大科技项目基金(批准号:2002F016);; 厦门市科技局重大科技项目基金(批准号:3502Z20021044