Enantiomeric enrichment of α-amino acid derivatives: recrystallization of N-Fmoc α-amino acid tert-butyl esters
摘要:
The optical purity of products derived from enantioselective reactions of the benzophenone imine of glycine tert-butyl esters can often be improved by conversion to the N-Fmoc alpha -amino acid tert-butyl esters followed by simple recrystallization. (C) 2001 Elsevier Science Ltd. All rights reserved.
Ru-Centered coordination complexes as a new phase transfer catalyst for alkylation of enolates and Michael additions
作者:Dimitrios Tzalis、Paul Knochel
DOI:10.1016/s0040-4039(99)00587-0
日期:1999.5
A novel phasetransfercatalysis based on a Ru(II)-polypyridyl complex 1 allows the fast alkylation of enolates and Michael additions under very mild conditions.
Recoverable Dendritic Phase-Transfer Catalysts that Contain (+)-Cinchonine-Derived Ammonium Salts
作者:Jordi Rull、José Juan Jara、Rosa M. Sebastián、Adelina Vallribera、Carmen Nájera、Jean-Pierre Majoral、Anne-Marie Caminade
DOI:10.1002/cctc.201600283
日期:2016.6.21
The asymmetric alkylation of a glycinate Schiff base with benzyl bromide is used as a benchmark reaction, and the dendrimeric catalyst that contains an allyl group on the O‐9 hydroxy group of the cinchonine units is the most active. The recovery and reuse of the catalyst are possible for five consecutive runs without loss of activity and with only a slight decrease in enantioselectivity. If other electrophiles
Asymmetric benzylation of a benzophenone Schiff’s base of alanine ethyl ester was successfully conducted using trans-3,4-dihydro-3,4-diaryldibenzo[c,g]phenanthrene-3,4-diol as a chiral source.
Palladium-catalyzed construction of amino acid derivatives possessing vicinal chiral quaternary and tertiary carbon centers at the α and β positions
作者:Daiji Ikeda、Motoi Kawatsura、Junichi Uenishi
DOI:10.1016/j.tetlet.2005.07.139
日期:2005.9
The palladium catalyzed regio- and diastereo-selective allylicalkylation of (R)-2-acetoxy-4-aryl-3-butene with N-(diphenylmethylidene)glycinate and N-(diphenylmethylidene)alaninate occurred. The stereochemistry was controlled by the use of o-(diphenylphosphino)carboxylic acid, and produced new amino acid derivatives possessing vicinal chiral quaternary and tertiary carbon centers at the α and β positions
Novel bis-N-[2-(diphenylphosphino)ferrocenylcarbonyl]diaminocyclohexane ligands: application in asymmetric allylic alkylation of imino esters with simple allyl carbonate
作者:Shu-Li You、Xue-Long Hou、Li-Xin Dai、Bo-Xun Cao、Jie Sun
DOI:10.1039/b003804k
日期:——
Several derivatives of ferrocene ligands with planar chirality
were investigated in palladium-catalysed asymmetric allylic alkylation of
iminoesters, in which bis-ferrocene ligand 7 containing a chiral pocket
showed good enantiocontrol in this reaction; the products having a
quaternary chiral center were obtained with up to 75.3% ee.