Study on the stereochemical control of dihydroxylation of vinyl epoxides and their derivatives
作者:Giuliana Righi、Emanuela Mandic’、Gaia Clara Mercedes Naponiello、Paolo Bovicelli、Ilaria Tirotta
DOI:10.1016/j.tet.2012.02.029
日期:2012.4
The results obtained from a study on the stereochemical control in the dihydroxylation of the double bond of vinyl epoxides and their derivatives (bromo derivatives, azido derivatives and vinyl aziridines) are presented herein. A significant diastereoselectivity was observed for the bromo derivatives, azido derivatives and N-protected vinyl aziridines, whereas vinyl epoxides and unprotected vinyl aziridines
Palladium-catalyzed Stereospecific Epoxide-opening Reaction of γ,δ-Epoxy-α,β-unsaturated Esters with Boric Acid Leading to γ,δ-Diol Derivatives with Double Inversion of Configuration
作者:Xiao-Qiang Yu、Atsushi Hirai、Masaaki Miyashita
DOI:10.1246/cl.2004.764
日期:2004.6
A new palladium-catalyzed epoxide-opening reaction of γ,δ-epoxy-α,β-unsaturated esters with boric acid has been developed, which proceeds stereospecifically giving rise to the corresponding γ,δ-dio...
In an attempt to replace harmful or carcinogenic solvents (such as dichloromethane, acetone, etc.) with non-harmful and greener ones, the possibility of performing four already developed ring-opening methodologies in a more eco-friendly media, such as DMC, has been investigated. The results show that the usual employed solvents (CH2Cl2, Et2O, CH3CN, etc.) can be easily replaced by DMC: not only the stereo- and regioselectivity is conserved, but also the work-up is simplified to a filtration, therefore reducing considerably the amount of solvents employed in the processes, and all the reactions are performed at room temperature, even the ones previously reported at low temperatures.
Stereoselective SN2′ alkylation reaction sequence of the γ,δ-epoxy α,β-unsaturated ester system via γ,δ-chlorohydrin intermediates by the use of a R3Al–CuCN reagent
A novel stereoselective SN2′ alkylation reaction sequence of the γ,δ-epoxy α,β-unsaturatedester system has been developed which involves a regioselective substitution reaction with chloride ions at the γ-position and a subsequent SN2′ alkylation reaction of the resulting γ-chloro-δ-hydroxy derivatives with a R3Al–CuCN reagent. The new methodology was demonstrated to be applicable to a variety of substrates
已经开发了γ,δ-环氧α,β-不饱和酯系统的新型立体选择性S N 2'烷基化反应序列,其涉及在γ-位与氯离子的区域选择性取代反应和随后的S N 2'烷基化反应R 3 Al–CuCN试剂合成的γ-氯代-δ-羟基衍生物。事实证明,该新方法可适用于多种底物,并提供各种δ-羟基-α-烷基-β,γ-不饱和酯,包括以高度立体选择性的方式在α-位带有季不对称碳原子的那些酯,以及高产。