微波辅助合成2-芳基-2-恶唑啉,5,6-二氢-4 H -1,3-恶嗪和4,5,6,7-四氢-1,3-恶氮杂s
摘要:
提出了通过微波辅助多磷酸(PPA)酯促进的ω-氨基醇的环化反应合成5至7元环亚氨基醚的第一个通用程序。使用聚磷酸乙酯/ CHCl 3有效地制备了2-芳基-2-恶唑啉和5,6-二氢-4 H -1,3-恶嗪。在无溶剂条件下,多磷酸三甲基甲硅烷基酯可合成迄今未报道的4,5,6,7-四氢-1,3-氧杂氮杂pine。该方法具有良好的收率和优异的收率,并且反应时间短。在手性底物中研究了PPA酯的反应机理和作用。
作者:David S. Laitar、John W. Kramer、Bryan T. Whiting、Emil B. Lobkovsky、Geoffrey W. Coates
DOI:10.1039/b913698c
日期:——
4-Substituted oxazolines, which are readily synthesized from naturally occurring α-amino acids, are converted efficiently and stereospecifically to β-amidoaldehydes in the presence of synthesis gas and catalytic dicobalt octacarbonyl.
Phosphorus-Based Organocatalysis for the Dehydrative Cyclization of <i>N</i>-(2-Hydroxyethyl)amides into 2-Oxazolines
作者:Farzaneh Soleymani Movahed、Siong Wan Foo、Shogo Mori、Saeko Ogawa、Susumu Saito
DOI:10.1021/acs.joc.1c02318
日期:2022.1.7
substrate scope and higher functional-group tolerance, providing the functionalized 2-oxazolines with retention of the configuration at the C(4) stereogenic center of the 2-oxazolines. Widely accessible β-amino alcohols can be used in this approach, and the cyclization of N-(2-hydroxyethyl)amides provides the desired 2-oxazolines in up to 99% yield. The mechanism of the reaction was studied by monitoring the
Cobalt-Catalyzed Regio- and Enantioselective Allylic Amination
作者:Samir Ghorai、Sahadev Shrihari Chirke、Wen-Bin Xu、Jia-Feng Chen、Changkun Li
DOI:10.1021/jacs.9b06035
日期:2019.7.24
earth-abundant cobalt-catalyzed highly branched- and enantioselectiveallylicamination of racemic branched allylic car-bonates bearing alkyl groups with both aromatic and aliphatic amines have been developed. The process allows rapid access of allylic amines in high yields with exclusively branched selectivity and excellent enantioselectivities (normally 99% ee) under mild reaction conditions.
Catalytic Asymmetric Hydrogenation of N-Boc-Imidazoles and Oxazoles
作者:Ryoichi Kuwano、Nao Kameyama、Ryuhei Ikeda
DOI:10.1021/ja201543h
日期:2011.5.18
Substituted imidazoles and oxazoles were respectively hydrogenated into the corresponding chiral imidazolines and oxazolines (up to 99% ee). The highly enantioselective hydrogenation was achieved by using the chiral ruthenium catalyst, which is generated from Ru(eta(3)-methallyl)(2)(cod) and a trans-chelating chiral bisphosphine ligand, PhTRAP. This is the first successful catalytic asymmetric reduction of 5-membered aromatic rings containing two or more heteroatoms.
Radical 1,4-aryl transfer in arylcarboxamides leading to phthalimides, biaryls and enantiomerically enriched β-arylethylamines
作者:Jeremy Robertson、Matthew J. Palframan、Stephen A. Shea、Kirill Tchabanenko、William P. Unsworth、Chase Winters
DOI:10.1016/j.tet.2008.07.118
日期:2008.12
5-exo Cyclisation of vinyl-, aryl- and alkyl-radicals onto the aryl group of arylcarboxamides is followed by beta-scission of the resulting spirocyclohexadienyl radicals with ejection of a carbamoyl radical. The fate of this radical depends on the substrate but, in the cases studied, either 5-endo cyclisation or direct reduction follows to give phthalimides, biaryls or beta-arylethylamines. (C) 2008 Elsevier Ltd. All rights reserved.