A transition-metal-free multicomponent reaction towards constructing chiral 2<i>H</i>-1,4-benzoxazine scaffolds
作者:Lixiang Zhu、Xiaoyu Ren、Juan Du、Jia-Hong Wu、Jian-Ping Tan、Jixing Che、Jianke Pan、Tianli Wang
DOI:10.1039/d0gc02134b
日期:——
transition-metal-free multicomponent cascade reaction of readily available α-halogenated ketones, ortho-aminophenols, and aldehydes using a novel dipeptide-based phosphonium salt catalyst was developed for the efficient construction of various 2H-1,4-benzoxazine derivatives with excellent functional-group tolerance. The method represents an unprecedented approach for trapping active 1,5-bifunctional intermediates
本文中,开发了一种使用新型的基于二肽的phospho盐催化剂的易于获得的α-卤代酮,邻氨基酚和醛的无过渡金属的多组分级联反应,以有效地构建各种2 H -1,4-苯并恶嗪具有出色的官能团耐受性的衍生物。该方法代表了一种空前的方法,用于捕获具有α-卤代酮的活性1,5-双功能中间体,以访问具有两个非立体诱导中心且具有两个立体生成中心的生物学上重要的苯并恶嗪支架。
Catalyst-free allylation of 2-aminophenol–derived aldimines with allyltrichlorosilane under thermal conditions
作者:Kesa Venkatanna、Chinnasamy Ramaraj Ramanathan
DOI:10.1016/j.tetlet.2017.08.012
日期:2017.9
Allylation of 2-aminophenol-derived aldimines using allyltrichlorosilane undercatalystfreeconditions has been developed. This reaction afforded the corresponding homoallylic amines in good to excellent yields (68–94%). The salicylaldehyde-derived aldimines as well as benzoylhydrazone also found to react with allyltrichlorosilane smoothly under the same conditions, to furnish the corresponding homoallylic
Enantioselective Strecker and Allylation Reactions with Aldimines Catalyzed by Chiral Oxazaborolidinium Ions
作者:Ki-Tae Kang、Sang Hyun Park、Do Hyun Ryu
DOI:10.1021/acs.orglett.9b02280
日期:2019.9.6
Chiral oxazaborolidiniumion (COBI)-catalyzed enantioselective nucleophilic addition reactions of aldimines using tributyltin cyanide and allyltributylstannane have been developed. Various α-aminonitriles and homoallylic amines were synthesized in high yield (up to 98%) with high to excellent enantioselectivity (up to 99% ee). A rational mechanistic model for the complex of COBI and aldimine is provided
The synthesis of highly substituted β-lactams was achieved by addition of air-stable ethyl(trimethylsilyl)acetate derivatives to N-(2-hydroxyphenyl)aldimine sodium salts in a THF-EtCN mixture. This reaction proceeds with moderate to good yields and diastereomeric ratio of up to 78:22. The reactivity of the N-(2-hydroxyphenyl)aldimine can be modified by simply changing the co-solvent from EtCN to MeCN to afford the cyanomethylated addition product.
Abnormal effect of hydroxyl on the longest wavelength maximum in ultraviolet absorption spectra for bis-aryl Schiff bases
作者:Chao-Tun Cao、Wei Zhou、Chenzhong Cao
DOI:10.1002/poc.3672
日期:2017.10
4‐HOArCH=NArY and XArCH=NArOH‐4′, and the second set consists of 2‐HOArCH=NArY and XArCH=NArOH‐2′. Their ultravioletabsorptionspectra were measured and investigated. A very interesting phenomenon was observed by analyzing their wave number νmax (cm−1) of longest wavelength maximum λmax (nm) of ultraviolet. Compared with the change regularity of the νmax of XArCH=NArY (where the X and Y excluded OH), the