Stereoselective intramolecular cycloadditions of homochiral nitrilimines as a source of enantiopure 2,3,3a,4,5,6-hexahydro-pyrrolo[3,4-c]pyrazoles
摘要:
Starting from the methyl esters of glycine, L-alanine.. L-phenylalanine and (S)-2-phenylglycine, we developed a synthetic route to the title compounds in the enantiopure form by means of a stereoselective intramolecular 1,3-dipolar cycloaddition of homochiral nitrilimines 5a-d. Fair to good overall product yields and high cycloaddition diastereoselectivity were obtained. (c) 2006 Elsevier Ltd. All rights reserved.
Lewis Acid Assisted Ring-Closing Metathesis of Chiral Diallylamines: An Efficient Approach to Enantiopure Pyrrolidine Derivatives
作者:Qian Yang、Wen-Jing Xiao、Zhengkun Yu
DOI:10.1021/ol047356q
日期:2005.3.1
Lewis acid assisted ring-closing olefin metathesis (RCM) of chiral diallylamines, using the second generation RCM ruthenium-based catalyst, leads to enantiopure pyrrolidine derivatives in 79-93% yields under very mild conditions. The scope of the olefin metathesis has been expanded.
Microwave-assisted ring-closing metathesis of diallylamines: a rapid synthesis of pyrrole and pyrroline derivatives
作者:Qian Yang、Xin-Yong Li、Hong Wu、Wen-Jing Xiao
DOI:10.1016/j.tetlet.2006.03.164
日期:2006.6
The ring-closing metathesis (RCM) reactions of diallylamines occurred under controlled microwave irradiation. In addition to the high reaction rate, the key features of the reaction are that it can be carried out without deactivation of the substrates and without the use of Lewis acids. (c) 2006 Elsevier Ltd. All rights reserved.
Lewis Acid Mediated Asymmetric [2,3]-Sigmatropic Rearrangement of Allylic Amines. Scope and Mechanistic Investigation
The first asymmetric [2,3]-sigmatropicrearrangement of achiral allylic amines has been realized by quaternization of the amines with an enantiomerically pure diazaborolidine and subsequent treatment with Et3N. The resultant homoallylic amines were obtained in good yields and excellent ee's. The observed diastereo- and enantioselectivities were rationalized by invoking a kinetically controlled process
Stereoselective intramolecular cycloadditions of homochiral nitrilimines as a source of enantiopure 2,3,3a,4,5,6-hexahydro-pyrrolo[3,4-c]pyrazoles
作者:Lara De Benassuti、Paola Del Buttero、Giorgio Molteni
DOI:10.1016/j.tetasy.2006.02.018
日期:2006.3
Starting from the methyl esters of glycine, L-alanine.. L-phenylalanine and (S)-2-phenylglycine, we developed a synthetic route to the title compounds in the enantiopure form by means of a stereoselective intramolecular 1,3-dipolar cycloaddition of homochiral nitrilimines 5a-d. Fair to good overall product yields and high cycloaddition diastereoselectivity were obtained. (c) 2006 Elsevier Ltd. All rights reserved.