Catalytic enantioselective synthesis of secondary alcohols using C2-symmetric diamino diol ligands
作者:Biao Jiang、Yan Feng、Jian-Feng Hang
DOI:10.1016/s0957-4166(01)00409-8
日期:2001.9
A newclass of diamino diols was evaluated as catalytic ligands in the enantioselective borane reduction of aromatic ketones and the enantioselective ethylation of arylaldehydes with diethylzinc. By variation of the substitution pattern on the ketone, e.e.s of up to 94% could be obtained by in situ borane reduction using 0.025 equiv. of the ligand at 35°C in THF. N,N,N′,N′-Tetramethyldiamino diol and
2-Pyridylsulfinamides as effective catalysts in the asymmetric alkylation of aldehydes with diethylzinc
作者:Kavirayani R. Prasad、Omkar Revu
DOI:10.1016/j.tet.2013.07.061
日期:2013.9
Chiral 2-pyridylsulfinamides were shown to be effective catalysts in the alkylation of aryl and alkyl aldehydes with diethylzinc providing the corresponding alcohols in excellent enantioselectivity. Sulfinamide catalysts possessing solitary chirality at the sulfur center produced the product phenethyl alcohol in good enantioselectivity. Diastereomeric sulfinamides possessing chirality at the carbon-bearing nitrogen and at the sulfur of the sulfinamide increased the enantioselectivity of the product alcohols up to >99%. However, there is no effect of the match-mismatch pair of sulfinamide diastereomers on the outcome of the chiral induction of the product phenethyl alcohols. It was conclusively proved that chirality at the sulfur center is mandatory for obtaining good enantioselectivity in the reaction. (C) 2013 Elsevier Ltd. All rights reserved.