Acetals of γ-oxo-α,β-unsaturated esters in nitrone cycloadditions. Regio- and stereochemical implications
摘要:
Several acetals of gamma -oxo-alpha,beta -unsaturated esters have been prepared, mainly from enantiopure C-2-symmetric diols, and their 1,3-dipolar cycloaddition to 2,3,4,5-tetrahydropyridine 1-oxide has been studied. All the reactions showed complete regio selectivity and a high preference for the endo approach of the reactants in the transition state. The enantiopure acetals derived from (cis, cis) -spiro [4.4]nonane- 1, 6-diol gave the highest diastereofacial selectivity. (C) 2001 Elsevier Science Ltd. All rights reserved.
Synthesis of new enantiomerically pure monoketals of p-benzoquinone with C2-symmetry
摘要:
Several new monoketals of p-benzoquinone with the structure of 1,3-dioxaspiro[4.5]deca-6,9-dien-8-one have been synthesised in enantiopure form by the straightforward reaction of the quinone with secondary C-2-symmetric 1,2-diols. The preparation of two new enantiopure C-2-1,2-glycolsis also reported. (C) 1999 Elsevier Science Ltd. All rights reserved.
The attempted stereoselective synthesis of chiral 2,2′-biindoline
作者:Mary J. Gresser、Steven M. Wales、Paul A. Keller
DOI:10.1016/j.tet.2010.06.035
日期:2010.8
The attempted first stereoselective synthesis of 2,2'-biindoline using a metathesis-Sharpless asymmetric dihydroxylation strategy results in the synthesis of the heterocycle in poor to modest stereoselectivity. Attempts to improve the ee by varying the heteroatom protecting groups in key intermediates did not enhance the outcome of the Sharpless AD reaction. Therefore a limitation of this AD reaction is the use of 1,4-substituted but-2-enes where these substituents are ortho-substituted aromatics. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.
Synthesis of new enantiomerically pure monoketals of p-benzoquinone with C2-symmetry
作者:Pedro de March、Marta Figueredo、Josep Font、Jordi Medrano
DOI:10.1016/s0040-4020(99)00400-7
日期:1999.6
Several new monoketals of p-benzoquinone with the structure of 1,3-dioxaspiro[4.5]deca-6,9-dien-8-one have been synthesised in enantiopure form by the straightforward reaction of the quinone with secondary C-2-symmetric 1,2-diols. The preparation of two new enantiopure C-2-1,2-glycolsis also reported. (C) 1999 Elsevier Science Ltd. All rights reserved.
Acetals of γ-oxo-α,β-unsaturated esters in nitrone cycloadditions. Regio- and stereochemical implications
作者:Ramon Alibés、Félix Busquè、Pedro de March、Marta Figueredo、Josep Font、Maria Esmeralda Gambino、Brian A. Keay
DOI:10.1016/s0957-4166(01)00294-4
日期:2001.7
Several acetals of gamma -oxo-alpha,beta -unsaturated esters have been prepared, mainly from enantiopure C-2-symmetric diols, and their 1,3-dipolar cycloaddition to 2,3,4,5-tetrahydropyridine 1-oxide has been studied. All the reactions showed complete regio selectivity and a high preference for the endo approach of the reactants in the transition state. The enantiopure acetals derived from (cis, cis) -spiro [4.4]nonane- 1, 6-diol gave the highest diastereofacial selectivity. (C) 2001 Elsevier Science Ltd. All rights reserved.