Various P∗-chiral phosphite-type ligands: their synthesis, stereochemistry and use in Pd-catalysed allylation
作者:Eduard B. Benetsky、Sergey V. Zheglov、Tatiana B. Grishina、Fliur Z. Macaev、Liudmila P. Bet、Vadim A. Davankov、Konstantin N. Gavrilov
DOI:10.1016/j.tetlet.2007.09.125
日期:2007.11
available modular phosphite, phosphoramidite and diamidophosphiteligands with P∗-stereocentres have been prepared from inexpensive optically active precursors. Using these novelligands, up to 91% ee was achieved in Pd-catalysedasymmetric allylic amination. The catalytic performance is affected greatly by the structure of the phosphocentre of the ligand.
Synthesis, structure, and reaction of chiral 2-azidoimidazolinium salts: (7aS)-3-azido-5,6,7,7a-tetrahydro-2-[(1R)-1-phenylethyl]-1H-pyrrolo[1,2-c]imidazolium hexafluorophosphate and 2-azido-1,3-bis[(S)-1-phenylethyl]imidazolinium hexafluorophosphate
Two chiral 2-azidoimidazolinium salts [(7aS)-3-azido-5,6,7,7a-tetrahydro-2-[(1R)-1-phenylethyl]-1H-pyrrolo[1,2-c]imidazolium hexafluorophosphate (2) and 2-azido-1,3-bis[(S)-1-phenylethyl]imidazolinium hexafluorophosphate (3)] were synthesized, and their structures were determined by X-ray single crystal structural analysis. Migratory amidation reaction of enol silyl ether with 3 proceeded, but good
两种手性2-叠氮基咪唑啉盐[(7a S)-3-叠氮基-5,6,7,7a-四氢-2-[(1 R)-1-苯乙基] -1 H-吡咯并[1,2- c ]合成了咪唑六氟磷酸盐(2)和2-叠氮基1,3-双[(S)-1-苯基乙基]咪唑啉六氟磷酸盐(3)],并通过X射线单晶结构分析确定了它们的结构。烯醇甲硅烷基醚与3进行迁移性酰胺化反应,但是在反应中未观察到良好的非对映选择性。
Synthesis of chiral diamines using novel 2-trichloromethyloxazolidin-4-one precursors derived from 5-oxo-proline and proline
作者:Mohamed Amedjkouh、Per Ahlberg
DOI:10.1016/s0957-4166(02)00579-7
日期:2002.10
Efficient syntheses of chiral vicinal diamines derived from (S)-oxo-proline and (S)-proline are described. The novel diastereomerically pure precursor (2R,5S)-2-trichloromethyl-1-aza-3-oxabicyclo-[3.3.0]-octan-4,8-dione 3 and its enantiomer are readily available by reaction of the inexpensive enantiomers of 5-oxo-proline with chloral. Compound 3 reacts with primary and secondary amines to afford the 5-oxo-prolylamides 4 in quantitative yield. In contrast, the (S)-proline-derived precursor (2R,5S)-2-trichloromethyl-1-aza-3-oxabicyclo[3.3.0]octan-4-one 6 gave (S)-N-formylprolylamides 9 and/or (S)-prolylamides 8 depending on the reaction conditions. Upon reduction with LiAlH4, amides 4 and 9 afforded the proline-derived (S)-2-(alkylaminomethyl)pyrrolidines 1 and (S)-N- methyl-2-(alkylaminomethyl)-pyrrolidines 5 in 70-90% yields. (C) 2002 Elsevier Science Ltd. All rights reserved.
Synthesis and characterization of chiral 1,2-diamines from 5-oxo-pyrrolidine-(S)-2-carboxylic acid
作者:Uwe Köhn、Andrea Schramm、Florian Kloß、Helmar Görls、Evelyn Arnold、Ernst Anders
DOI:10.1016/j.tetasy.2007.07.012
日期:2007.7
Unsymmetrical chiral secondary vicinal diamines were synthesized by applying a modified three-step reaction. The key step in this sequence is a primary amine mediated ring opening reaction of a diastereomeric oxazolidinone derivative. A possible mechanism for this step is described. (c) 2007 Elsevier Ltd. All rights reserved.