据报道,高效手性酯烯酸酯-亚胺缩合可产生具有出色的反式-顺式或反式-非对映体选择性的3,4-二取代的β-内酰胺。手性信息包括在缩合的亲电子伙伴中,名义上为手性α-,β-甲硅烷氧基-或烷氧基-N-三甲基甲硅烷基亚胺。高非对映选择性是由反应介质中存在的金属阳离子的正确选择和羟基保护基团的性质决定的。通过这种方法,已经获得了许多氮杂环丁酮类化合物,它们是合成商业上感兴趣的β-内酰胺类抗生素的中间体。报道了如此获得的氮杂环丁酮的完全归属的1 H和13 C NMR谱。
β-Lactams from ester enolates and N-TMSimines: Enantioselective synthesis of (6R, 7S)-1β-3-dimethyl-3-isocephem
作者:Gianfranco Cainelli、Mauro Panunzio、Elisa Bandini、Giorgio Martelli、Giuseppe Spunta、Marco Da Col
DOI:10.1016/0040-4020(95)98703-k
日期:1995.4
lactic aldehyde (4) and cyclic silyl derivative of glycine (2). The elaboration of hydroxyethyl side chain was carried out by functional group interchange (FGI) of the hydroxyl group by a thioacetoxy group, and finally six-membered ring assembly followed by attachment of necessary appendage to N-7 nitrogen atom.
well as reaction conditions. Abinitiostudies at MP2/6−31G* and QCISD(T)/6−311G** levels on model compounds provide a rationalization of the experimental results obtained. From the experimental as well as theoretical data it is clear that the presence of the silyl enol group in the intermediate azadiene is crucial in its stabilisation and plays a fundamental role in the conrotatory ringclosure and,
A general approach to the solution phase parallel synthesis of perhydrooxazin-4-ones, which allows the preparation of milligram quantities of each individual member, is reported. An efficient purification; method, using as "Sequestration Enabling Reagent" (SER) aminomethylpolystyrene resin in the presence of trimethylorthoformate is also described. (C) 1998 Elsevier Science Ltd. All rights reserved.
Synthesis of NH -3-phenylsulfanyl- and NH -3-benzylsulfanyl-azetidinones from 1-phenylsulfanyl- or 1-benzylsulfanyl-3-aza-1,3-dienes
The syntheses of NH-3-phenylsulfanyl- and NH-3-benzylsulfanyl-azetidinones, starting from 1-phenylsulfanyl- or 1-benzylsulfanyl-2-trimethylsilyloxy-3-aza-1,3-dienes are reported. (C) 2003 Elsevier Ltd. All rights reserved.
Hetero Diels−Alder vs Electrocyclic Reaction of Azadiene: Selective Synthesis of All Stereoisomers of Threonines