Te-1-Acylmethyl and Te-1-Iminoalkyl Telluroesters: Synthesis and Thermolysis Leading to 1,3-Diketones and O-Alkenyl and O-Imino Esters
摘要:
A series of Te-1-acylmethyl carbotelluroates was prepared in good isolated yields from the reaction of potassium carbotelluroates with -haloketones in acetonitrile. Thermolysis of the telluroesters afforded vinyl esters in 20-50% yields, while treatment of the carbotellurorates with potassium t-butanolate led to 1,3-diketones in 30-75% yields with the liberation of black tellurium. The reaction of potassium carbotelluroates with -haloaceto oximes gave O-acyl oximes in 50-70% yields via Te-1-iminomethylcarbotelluroates.
Oxime Esters as Acylating Agents in the Aminolysis Reaction. A Simple and Chemoselective Method for the Preparation of Amides from Amino Alcohols
作者:Susana Fernández、Emma Menéndez、Vicente Gotor
DOI:10.1055/s-1991-26553
日期:——
Oxime esters, such as acetone O-alkanoyl-, O-alkenoyl- or O-benzyloxycarbonyloximes, react with amines under extremely mild conditions to give the corresponding amides in very good yield. When amino alcohols are used a total chemoselectivity is observed.
We describe herein a palladium-catalyzed Heck-type reaction of O-acetyl ketoximes and allylicalcohols to pyridines. This protocol allows robust synthesis of pyridines and azafluorenones in good to excellent yields with...
Generation of chromioenamines by reduction of O-acetyloximes with chromium(ii) and their application
作者:Kazuhiko Takai、Noriko Katsura、Yuji Kunisada
DOI:10.1039/b105357b
日期:——
Chromioenamines can be generated by treatment of O-acetyloximes with chromium(II) via two steps of one-electron reduction and successive isomerization, and the species react with aldehydes to give gamma-amino alcohols after reduction with LiAlH4.
Chemoenzymatic Synthesis of a Glycolipid Library and Elucidation of the Antigenic Epitope for Construction of a Vaccine Against Lyme Disease
作者:Gunthard Stübs、Bernd Rupp、Ralf R. Schumann、Nicolas W. J. Schröder、Jörg Rademann
DOI:10.1002/chem.200902205
日期:2010.3.15
prevalent antigen frequently recognized by antibodies in late‐stage LD. Here we report a convenient route for the chemical synthesis of ACGal by employing a combination of chemical synthesis steps with enzymatic transformations. This synthesized molecule was compared with bacterial extracts by immunoblots with patient sera, confirming the preserved antigenicity. Next, a glycolipidlibrary derived from
莱姆病(LD)是欧洲,北美和亚洲最常见的壁虱传播疾病。LD的病原体是Borrelia burgdorferi sensu lato组的螺旋体,其脂质含量为干重的25–30%。主要糖脂胆固醇6- ö酰基-β- d -galactopyranoside(ACGal),存在于博氏疏螺旋狭义,B. afzelii,和B. garinii,是一种特异且高度流行的抗原,经常被晚期LD的抗体识别。在这里,我们报告了通过化学合成步骤与酶促转化相结合的化学合成ACGal的便捷途径。通过用患者血清进行免疫印迹将该合成的分子与细菌提取物进行比较,确认了保留的抗原性。接下来,设计并合成了衍生自具有脂肪酰基部分变化的天然分子的糖脂文库和其中胆固醇已被取代的衍生物。化学结构通过1D和2D NMR光谱法和质谱法确认。将天然和合成的糖脂用于免疫印迹,以确定患者血清中抗体识别的表位。通过这种方法,我们可以证明半乳糖 胆固醇
Towards the selective acylation of secondary hydroxyl groups of carbohydrates using oxime esters in an enzyme-catalyzed process
作者:Rosalino Pulido、Vicente Gotor
DOI:10.1016/0008-6215(94)90005-1
日期:1994.1
alkyloxycarbonylation. A lipase from Pseudomonas cepacia catalyzed also the regioselectiveacylation of the primary hydroxylgroup of 1 and 2 when 1,4-dioxane was used as solvent. Moreover, this lipase was a suitable biocatalyst for the acylation of the secondary HO-3 of 6- O (benzyloxy)carbonyl derivatives of 2-deoxy- d -hexoses. Subsequent deprotection of the primary hydroxylgroup through catalytic hydrogenation