通过气相色谱分析随后分离的阿魏木霉菌株11的发酵肉汤,然后使用Finnigan MAT GCQ仪器进行质谱检测。在C18和硅胶柱中进行预分离后,分别获得十九个吡喃酮和二氧戊环衍生物以及两种脂族酯。其中,四种二氧戊环衍生物先前尚未鉴定。发现主要成分为5,5'-二甲基-2H-吡喃-2-on。用于确定保留时间和峰面积(以离子数测量)的相对标准偏差分别为0.1%和4.5%。
A novel method for generation of carbenoid from α-chloro sulfoxides: A new and versatile procedure for one-carbon homologation of carbonyl compounds to carbonyl compounds having an α-alkyl substituent
Addition of the carbanion of 1-chloroalkyl p-tolyl sulfoxides to carbonylcompound gave the adducts, which were treated with a base followed by t-butyllithium to afford one-carbon homologated carbonylcompounds having an alkyl group at the α-position, via the β-oxido carbenoids, in moderate to good yields.
A highly efficient and selective rearrangement reaction of bromohydrins to aldehydes mediated by CF3CO2ZnEt was described. The secondary and tertiary aldehydes were prepared under mild conditions in good to excellent yields (85–99%). The scope and limitations of this rearrangement process were also investigated.
描述了由CF 3 CO 2 ZnEt介导的溴代醇对醛类的高效选择性重排反应。仲醛和叔醛是在温和的条件下以良好至极佳的收率(85–99%)制备的。还研究了这种重排过程的范围和局限性。
Et<sub>2</sub>Zn-Mediated Rearrangement of Bromohydrins
作者:Lezhen Li、Peijie Cai、Qingxiang Guo、Song Xue
DOI:10.1021/jo800231s
日期:2008.5.1
and highly efficient method for the rearrangement of bromohydrins mediated by Et2Zn to synthesize carbonylcompounds was described. Various β-bromo alcohols were treated with 0.6 equiv of Et2Zn to form a zinc complex in CH2Cl2 at room temperature for 2 h, followed by 1,2-migration to give the corresponding carbonylcompounds. This remarkable and clean rearrangement is general for acyclic and cyclic bromohydrins
Metal-free, Oxidative α-Coupling of Aldehydes with Amine Nucleophiles for the Preparation of Congested C(sp<sup>3</sup>)–N Bonds
作者:Nomaan M. Rezayee、Matilde Rusbjerg、Maximilian Marx、Sif T. Linde、Karl Anker Jørgensen
DOI:10.1021/acs.joc.1c01937
日期:2022.2.4
undertaken to foster dihydroquinoxaline-type products. A solvent exchange to the polar, aproticsolvent, MeNO2, proved critical to facilitate intermolecular α-C–N bond formation with a wide range of amine coupling partners (N-heterocycles, N,N-diaryl amines, and anilines). Application of the solvent exchange to the enantioselective SN2-DKR manifold provided distinct regimes leading to refinement in yield and
本文公开了应用氮基亲核试剂对 α-支链醛进行直接 α-胺化。在有机催化的氧化条件下,α-支链醛被加到它们的亲电子合成子上,随后被各种亲核胺取代,形成四取代的叔中心。以前曾采用类似的策略来形成拥挤的 C-C、C-O 和 C-S 键;然而,当将该方法扩展到包括 C-N 键时,却收到了不令人满意的结果。最初,进行分子内α-胺化反应以促进二氢喹喔啉型产物。与极性非质子溶剂 MeNO 2的溶剂交换证明对于促进与多种胺偶联配偶体(N-杂环、N,N-二芳基胺和苯胺)。将溶剂交换应用于对映选择性 S N 2-DKR 歧管提供了不同的方案,从而提高了产率和对映选择性。
Enantioselective α‐Etherification of Branched Aldehydes via an Oxidative Umpolung Strategy
作者:Johannes N. Lamhauge、Vasco Corti、Yidong Liu、Karl Anker Jørgensen
DOI:10.1002/anie.202105721
日期:2021.8.16
p-Fluoranil enables the preparation of α-aryloxylated aldehydes using phenol nucleophiles in up to 91 % ee, following either a one-step or a two-step, one-pot protocol. DDQ allows for a more general etherification protocol in combination with a broader range of alcohol nucleophiles with enantioselectivities up to 95 % ee. Control experiments and isolation of a key quinol intermediate supports a mechanism
饱和羰基化合物通过其烯醇化物类似物在 α 位具有固有的亲核性。在苯醌氧化剂的存在下,外消旋α-支化醛的α-位极性反转,允许使用现成的氧基亲核试剂和氨基酸衍生的伯胺催化剂进行对映选择性醚化。对苯醌氧化剂的调查发现对氟苯胺和 DDQ 是合适的反应伙伴。p- Fluoranil 可以使用苯酚亲核试剂制备 α-芳氧基化醛,ee含量高达 91%,遵循一步或两步,一锅协议。DDQ 允许与更广泛的醇亲核试剂结合使用更通用的醚化方案,对映选择性高达 95% ee。关键醌醇中间体的控制实验和分离支持通过 S N 2 动态动力学分辨率进行的机制。这些研究为氨基催化 umpolung 概念提供了基础,该概念允许在醛的 α 位不对称构建叔醚。