A facile method for the synthesis of enantiopure α-unsubstituted β-hydroxy esters
摘要:
One-pot deacylation-debromination reactions involving the transesterification of the initial chiral beta-bromo-beta-hydroxy thioimide aldol adducts and subsequent Al-Hg mediated reductive cleavage of the C-Br bond allow for a facile synthesis of enantiopure beta-hydroxy esters. (C) 2000 Published by Elsevier Science Ltd.
Dimethylzinc-Mediated, Oxidatively Promoted Reformatsky Reaction of Ethyl Iodoacetate with Aldehydes and Ketones
作者:Pier Giorgio Cozzi、Alessandro Mignogna、Paola Vicennati
DOI:10.1002/adsc.200700572
日期:2008.5.5
A practical and general Reformatskyreaction, promoted by oxidants and mediated by dimethylzinc, is described. The reaction is fast and runs at 0 °C with aldehydes and ketones, under mild reaction conditions. Preliminary results obtained for the enantioselective version show that inexpensive chiral amino alcohols could be used in the challenging formation of enantioenriched quaternary stereogenic centers
An in situ procedure for catalytic, enantioselective acetate aldol addition. Application to the synthesis of (R)-(−)-epinephrine
作者:Robert A. Singer、Erick M. Carreira
DOI:10.1016/s0040-4039(96)02515-4
日期:1997.2
experimental procedure for the enantioselective, catalyticacetate aldol addition reaction. The addition of Me3SiCl and Et3N circumvents the azeotropic removal of the released isopropanol upon treating ligands 1 and 2 with Ti(OiPr)4. Importantly, this new procedure maintains the salient features of the catalytic process we originally described: high yields and enantioselectivities, low catalyst loads, and
我们报道了催化剂3的原位制备,其实质上简化了对映选择性的,催化的乙酸酯羟醛加成反应的实验程序。Me 3 SiCl和Et 3 N的添加避免了用Ti(O i Pr)4处理配体1和2时共沸除去释放的异丙醇。重要的是,这种新方法保持了我们最初描述的催化过程的显着特征:高收率和对映选择性,低催化剂负载以及便捷的反应时间和温度。我们已将新程序应用于(R来自商业试剂的)-(-)-肾上腺素,总产率为45%。
[2.2]Paracyclophane-based carbene–copper catalyst tuned by transannular electronic effects for asymmetric boration
作者:Jianqiang Chen、Wenzeng Duan、Zhen Chen、Manyuan Ma、Chun Song、Yudao Ma
DOI:10.1039/c6ra14404g
日期:——
of planar chiral carbene–copper complexes based on the [2.2]paracyclophane backbone with a pseudo-ortho substitution pattern have been synthesized and applied to asymmetric β-boration of α,β-unsaturatedesters. As a result, transannular electronic effects of the substituent of the chiralcatalyst have significant influence on the catalytic performance. A variety of chiral β-hydroxyl esters were obtained
Asymmetric aldol-type reaction between both achiral ketene silyl acetals of acetic acid esters and aldehydes by the use of a chiral promoter
作者:Teruaki Mukaiyama、Shū Kobayashi、Tetsuya Sano
DOI:10.1016/s0040-4020(01)85587-3
日期:——
aldol-type reaction between achiral ketene silyl acetals of acetic acid esters and achiral aldehydes is successfully carried out by the use of a chiral promoter, a combined use of chiral diamine coordinated tin(II) trifluoromethanesulfonate (tin(II) triflate) and tributyltin fluoride. The structure of this new promoter and the mechanism of the present asymmetric aldol-type reaction are discussed.
Asymmetric Aldol-type Reaction between Both Achiral Ketene Silyl Acetals and Aldehydes by the Use of a Chiral Promoter
作者:Shu Kobayashi、Tetsuya Sano、Teruaki Mukaiyama
DOI:10.1246/cl.1989.1319
日期:1989.8
Highly enantioselective aldol-type reaction of achiral ketene silyl acetals with achiral aldehydes is carried out by the use of a chiral promoter, a combined use of chiral diamine coordinated tin(II) triflate and tributyltin fluoride.