S<sub>N</sub>2 vs. E2 on quaternary centres: an application to the synthesis of enantiopure β<sup>2,2</sup>-amino acids
作者:Alberto Avenoza、Jesús H. Busto、Francisco Corzana、Gonzalo Jiménez-Osés、Jesús M. Peregrina
DOI:10.1039/b400282b
日期:——
SN2 and E2 competing reactions in cyclic sulfamidates can be modulated by the change of an amide group to an ester group attached to the quaternary carbon activated for the nucleophilic attack, allowing an easy approach to enantiopure α,α-disubstituted β-amino acids.
Influence of substitution pattern on intramolecular alkylidene carbene insertion reactions
作者:Ahmed Bourghida、Vincent Wiatz、Martin Wills
DOI:10.1016/s0040-4039(01)01853-6
日期:2001.12
A series of intramolecular alkylidene insertionreactions have been investigated. The nature of the substituents is demonstrated to have a dramatic effect on the outcome. In one example a novel rearrangement is observed.
Understanding the Unusual Regioselectivity in the Nucleophilic Ring-Opening Reactions of <i>g</i><i>em</i>-Disubstituted Cyclic Sulfates. Experimental and Theoretical Studies
作者:Alberto Avenoza、Jesús H. Busto、Francisco Corzana、José I. García、Jesús M. Peregrina
DOI:10.1021/jo034178q
日期:2003.5.1
The regioselectivity of the nucleophilic ring-openingreactions of three gem-disubstituted cyclic sulfates with sodium azide has been studied from both experimental and theoretical viewpoints. It is found that, depending on the substituent present in the cyclic sulfate, the reaction displays reversed regioselectivity, which allows one or another regioisomer to be obtained with selectivities greater
An alternative approach to (S)- and (R)-2-methylglycidol O-benzyl ether derivatives
作者:Alberto Avenoza、Carlos Cativiela、Jesús M. Peregrina、David Sucunza、Marı́a M. Zurbano
DOI:10.1016/s0957-4166(01)00230-0
日期:2001.6
This report describes the gram scale synthesis of (S)- and (R)-2,2,4-trimethyl-4-(hydroxymethyl)-1,3-dioxolanes using the Sharpless asymmetric dihydroxylation (AD) of the Weinreb amide of 2-methyl-2-propenoic acid. The 2-methylglycerol acetonides resultant from protection of the AD products were used as starting materials in the synthesis of O-benzyl ethers of the valuable C4-chiral building blocks (S)- and (X)-2-methylglycidol. (C) 2001 Elsevier Science Ltd. All rights reserved.
Preparation of 2(R) and 2(S) methyl-2-methylglycerates
作者:Juan B. Rodríguez、Sanford P. Markey、Herman Ziffer
DOI:10.1016/s0957-4166(00)86020-6
日期:1993.1
Optically pure samples of both enantiomers of methyl 2,3-dihydroxy-2-methylpropanoate were prepared by a chromatographic separation of their (-)-menthyl esters followed by hydrolysis and methylation. Their absolute stereochemistries were established by conversion into their 3-0-acetyl derivatives, compounds of established configuration. NMR and CG-MS methods of determining the optical purities of the diols are described.