Conformational restriction approach to BACE1 inhibitors II: SAR study of the isocytosine derivatives fixed with a cis-cyclopropane ring
摘要:
To improve the efficacy of the conformationally restricted BACE1 inhibitors, structural modifications were investigated using two strategies: (a) modification of the terminal aromatic ring and (b) insertion of a spacer between the aromatic rings. In the latter approach, another type of inhibitor 17 bearing an ethylene spacer between two aromatic rings was found to exhibit good BACE1 inhibitory activity, while the corresponding conformationally unrestricted compound 25 showed no activity. This result revealed an interesting effect of a conformational restriction with a cyclopropane ring. (C) 2013 Elsevier Ltd. All rights reserved.
Silver-Catalyzed Hydroboration of C–X (X = C, O, N) Multiple Bonds
作者:Vipin K. Pandey、Chandra Shekhar Tiwari、Arnab Rit
DOI:10.1021/acs.orglett.1c00106
日期:2021.3.5
AgSbF6 was developed as an effective catalyst for the hydroboration of various unsaturated functionalities (nitriles, alkenes, and aldehydes). This atom-economic chemoselective protocol works effectively under low catalyst loading, base- and solvent-free moderate conditions. Importantly, this process shows excellent functional group tolerance and compatibility with structurally and electronically diverse
Cobalt-Catalyzed Hydroboration of Alkenes, Aldehydes, and Ketones
作者:Sem Raj Tamang、Deepika Bedi、Sara Shafiei-Haghighi、Cecilia R. Smith、Christian Crawford、Michael Findlater
DOI:10.1021/acs.orglett.8b02775
日期:2018.11.2
An operationally convenient and general method for hydroboration of alkenes, aldehydes, and ketones employing Co(acac)3 as a precatalyst is reported. The hydroboration of alkenes in the presence of HBpin, PPh3, and NaOtBu affords good to excellent yields with high Markovnikov selectivity with up to 97:3 branched/linear selectivity. Moreover, Co(acac)3 could be used effectively to hydroborate aldehydes
报道了使用Co(acac)3作为预催化剂对烯烃,醛和酮进行氢硼化的操作方便且通用的方法。在HBpin,PPh 3和NaO t Bu存在下,烯烃进行硼氢化可提供良好的产率,并具有高的马尔可夫尼科夫选择性和高达97:3的支链/线性选择性。而且,在温和的反应条件下,在不存在添加剂的情况下,Co(acac)3可有效地用于硼氢化醛和酮。醛基的分子间和分子内化学选择性还原发生在酮官能团之上。
Selective Synthesis of Alkylboronates by Copper(I)-Catalyzed Borylation of Allyl or Vinyl Arenes
作者:Yanmei Wen、Jianying Xie、Chunmei Deng、Chaode Li
DOI:10.1021/jo502606x
日期:2015.4.17
An efficientcopper-catalyzedborylation reaction of allyl or vinyl arenes with bis(pinacolato)diboron has been developed, without using ligands. Markovnikov-selectivity is observed in the borylation of allyl arenes with bis(pinacolato)diboron, while the regioselectivity is completely opposite when styrene derivatives are used as substrates. A mechanism involving Cu–B species regioselectively adding
Highly efficient and practical hydroboration of alkenes has been catalyzed by an inexpensive and air-stable cobalt(II) coordination polymer (CP) in the presence of KOtBu. Complete conversion of alkenes to alkylboronates were performed within just 5 min with low catalyst loading (0.025 mol %), achieving the record high turnover frequencies of up to 47 520 h–1. For a range of vinylarenes, unusual Markovnikov
在KO t Bu存在下,廉价且空气稳定的钴(II)配位聚合物(CP)催化了烯烃的高效,实用的硼氢化反应。在短短5分钟内以低催化剂负载量(0.025 mol%)将烯烃完全转化为烷基硼酸酯,实现了高达47 520 h –1的创纪录高周转率。对于一定范围的乙烯基芳烃,观察到了异常的马尔可夫尼科夫选择性。
Cobalt-Catalyzed Regioselective Hydroboration of Terminal Alkenes
作者:Guoqi Zhang、Jing Wu、Man Wang、Haisu Zeng、Jessica Cheng、Michelle C. Neary、Shengping Zheng
DOI:10.1002/ejoc.201701047
日期:2017.10.17
Cobalt(II) catalysts based on flexible PNP or NNN ligands were explored for the regioselective hydroboration of alkenes. A known CoII–PNP pincercomplex was found to efficiently catalyze alkene hydroboration with excellent anti-Markovnikov selectivity, whereas a newly synthesized dinuclear CoII–NNN complex was found to catalyze the hydroboration of a range of aromatic terminal alkenes with good Markovnikov