Carbonylative Ring Opening of Terminal Epoxides at Atmospheric Pressure
作者:Scott E. Denmark、Moballigh Ahmad
DOI:10.1021/jo7014455
日期:2007.12.1
[GRAPHICS]The carbonylative opening of terminal epoxides under mild conditions has been developed using CO2-(CO)(8) as the catalyst. Under I atm of carbon monoxide and at room temperature in methanol, propylene oxide is converted to methyl 3-hydroxybutanoate in up to 89% yield. This transformation is general for many terminal epoxides bearing alkyl, alkenyl, aryl, alkoxy, chloromethyl, phthalimido, and acetal functional groups. The opening takes place without epimerization at the secondary stereocenter.
Enantioselective synthesis induced by chiral epoxides in conjunction with asymmetric autocatalysis
5-Pyrimidyl alkanol with an enantiomeric excess of up to 96% was formed using chiral epoxides as a chiral initiator in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde, in conjunction with asymmetric autocatalysis. (C) 2004 Elsevier Ltd. All rights reserved.
Humicola lanuginosa lipase-catalyzed enantioselective resolution of β-hydroxy sulfides: versatile synthons for enantiopure β-hydroxy sulfoxides
Humicola lanuginosa lipase-catalyzed acylation of beta -hydroxy sulfides provides both the (R)- and (S)-enantiomers in high enantiomeric purity. In two cases the resolved hydroxy sulfides were oxidized to give beta -hydroxy sulfoxides in > 99% e.e. The effect of substituents on enantioselectivity is discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.
Chemoenzymatic synthesis of β-hydroxyl-sulfoxides by a two-step reaction of enzymatic reduction using Pseudomonas monteilii species and sulfoxidation with chiral titanium complexe
A two-step enantioselective synthetic strategy for the preparation of β-hydroxyl-sulfoxides has been described. With the enzymatic reduction of β-ketosulfides using Pseudomonas monteilii ZMU-T04 followed by the asymmetric sulfoxidation with Ti(OiPr)4/(S)-BINOL complexe, a wide range of corresponding β-hydroxyl-sulfoxide derivatives were smoothly obtained with excellent stereoselectivities (up to 99:1
已经描述了用于制备β-羟基亚砜的两步对映体选择性合成策略。通过使用Montesii monteilii ZMU-T04酶促还原β-酮硫醚,然后用Ti(O i Pr)4 /(S)-BINOL络合物进行不对称硫氧化,可以顺利地获得各种相应的β-羟基-亚砜衍生物。出色的立体选择性(高达99:1 dr和> 99%ee)。在控制实验的基础上,还提出了在β-羟基硫醚不对称硫氧化反应中,钛配合物可能存在的螯合物结构。