研究了以1-芳基-2-氟乙醇为亲核试剂对4-氯喹唑啉和6-溴-4-氯噻吩并[2,3- d ]嘧啶的亲核芳香取代反应,重点是结合环境可接受的溶剂使用碳酸盐碱。转化率取决于溶剂性质,亲核试剂的酸度和碱的性质。通过使用乙腈作为反应介质并且以K 2 CO 3为碱,可以将2,2,2-三氟-,2,2-二氟-和2-氟-1-苯基乙醇有效地偶联到4-氯嘧啶上。或者,使用Cs 2 CO 3,可以缩短这些底物的反应时间,并且非氟化醇的偶联也进行得很好。还发现叔丁醇是氟代醇转化中合适的反应介质。对4-烷氧基嘧啶的水解稳定性的测试表明,氟化和非氟化衍生物在酸性条件下均不稳定,而在碱性介质中,氟烷氧基衍生物比其非氟化衍生物更稳定。
Steric vs. electronic effects in the Lactobacillus brevis ADH-catalyzed bioreduction of ketones
作者:Cristina Rodríguez、Wioleta Borzęcka、Johann H. Sattler、Wolfgang Kroutil、Iván Lavandera、Vicente Gotor
DOI:10.1039/c3ob42057d
日期:——
(LBADH) is an alcohol dehydrogenase that is commonly employed to reduce alkyl or aryl ketones usually bearing a methyl, an ethyl or a chloromethyl as a small ketone substituent to the corresponding (R)-alcohols. Herein we have tested a series of 24 acetophenone derivatives differing in their size and electronic properties for their reduction employing LBADH. After plotting the relative activity against
A highly efficient and chemoselectivetransferhydrogenation of ketones in water has been successfully achieved with our newly developed catalyst. Simple ketones, as well as α- or β-functionalized ketones, are readily reduced. Formic acid is used as a traceless hydride source. At very low catalyst loading (S/C = 10 000 in most cases; S/C = 50 000 or 100 000 in some cases), the iridiumcatalyst is impressively
使用我们最新开发的催化剂,已成功实现了水中酮的高效化学选择性转移加氢。简单的酮以及α-或β-官能化的酮容易被还原。甲酸用作无痕氢化物源。在非常低的催化剂负载(小号/ ç = 10 000在大多数情况下;小号/ C ^ = 50 000或100 000在一些情况下)时,铱催化剂是减少在良好酮类到优异的产率令人印象深刻的高效率。TOF值可高达26000 mol mol -1 h -1。各种官能团是良好耐受的,例如杂芳基,芳氧基,烷氧基,卤素,氰基,硝基,酯,尤其是酸性亚甲基,苯酚和羧酸基团。
Enzymatic synthesis of enantiopure aromatic secondary alcohols (including substituted, hetero-aromatic and bicyclic structures) was carried out using halophilic alcohol dehydrogenase ADH2 from Haloferax volcanii (HvADH2). This enzyme showed an unprecedented substrate scope and absolute enatioselectivity. The cofactor NADPH was used catalytically and regenerated in situ by the biocatalyst, in the presence
The reinvestigation of the kinetics of the reactions of fluorodi(4-nitrophenyl)ethanes with sodium methoxide in methanol
作者:Kenneth T. Leffek、Grzegorz Schroeder
DOI:10.1139/v82-231
日期:1982.7.1
The procedure previously described for the preparation of 1-fluoro-2,2,-di(4-nitrophenyl)ethane actually yields 1,1,2-tri-(4-nitrophenyl)ethane. 1-Fluoro-2,2-di(4-nitrophenyl)ethane has been prepar...