(S)-Threonine/α,α-(S)-diphenylvalinol-derived chiral ionic liquid: an immobilized organocatalyst for asymmetric syn-aldol reactions
摘要:
Chiral ionic liquids containing (S)- or (R)-threonine amide and alpha,alpha-(S)-diphenylvalinol units were synthesized In the presence of the (S)-threonine-derived catalyst reactions between ketones with secondary carbon atom(s) at the alpha-position with respect to the carbonyl group and aromatic (heteroaromatic) aldehydes afforded the corresponding syn-aldols in high yields (up to 99%) and with high diastereo-(syn/anti up to 97:3) and enantioselectivity (up to 99% ee), which was maintained over three reaction cycles. (C) 2011 Elsevier Ltd. All rights reserved.
study on the enantioselective organocatalyzed cross-aldol reaction of 1-benzothiophene and thiophenecarbaldehydes with different ketones. The reactions were conducted at 0 °C or room temperature to afford the corresponding adducts in high yields and good to excellent ee using different organocatalysts. Interestingly, using (S)-pyrrolidine tetrazole and acetoxyacetone an inversion of the aldol regiochemistry
Pepsin-catalyzed direct asymmetric aldol reactions for the synthesis of vicinal diol compounds
作者:Ling-Yu Li、Da-Cheng Yang、Zhi Guan、Yan-Hong He
DOI:10.1016/j.tet.2015.01.061
日期:2015.3
The catalytic promiscuity of pepsin from porcine gastric mucous was observed in catalysis of the direct asymmetric aldol reactions of aromaticaldehydes with acetones, which were substituted by hydroxy-, dihydroxy-, methoxy- and benzyloxy- for the synthesis of diol compounds in acetonitrile. This biocatalysis was also applicable to the aldol reactions of cyclic or hetereocyclic ketones with aromatic