NBS-Promoted Reactions of Symmetrically Hindered Methylphenols via <i>p</i>-Benzoquinone Methide
作者:Woonphil Baik、Hyun Joo Lee、Jung Min Jang、Sangho Koo、Byeong Hyo Kim
DOI:10.1021/jo9911185
日期:2000.1.1
Symmetrically hindered methylphenols 1 react smoothly with NBS to form transient intermediates, p-benzoquinone methides (BM), which can be further processed to give hydroxybenzaldehydes in the presence of DMSO. This reaction is initiated by the formation of the phenoxy radical, followed by disproportionation to afford BM. None of the side-chain-brominated product is observed. The existence of BM is
the mesopores, and serve as an efficient heterogeneous catalyst for the synthesis of heterocycle-containing diarylmethanes via Friedel-Crafts-like alkylation of (hetero)arenes by heterobenzyl acetates under mild reaction conditions without requiring any additives or an inert atmosphere. Using this strategy, the gram-scale synthesis of indole-containing diarylmethane 13 has been accomplished in good yield
This study reports a mild and efficient synthetic protocol for the synthesis of symmetrical and unsymmetrical diarylmethanes (DAMs). Using DMSO as the C1 source and TMSOTf as the Lewis acid promoter, a series of functionalized symmetrical and unsymmetrical DAMs were synthesized in high yields. Gratifyingly, DMSO plays a dual role as a solvent and a C1 source and can also be replaced with its deuterated
本研究报告了一种用于合成对称和不对称二芳基甲烷 (DAM) 的温和有效的合成方案。使用 DMSO 作为 C 1源和 TMSOTf 作为路易斯酸促进剂,以高产率合成了一系列功能化的对称和非对称 DAM。令人欣慰的是,DMSO 作为溶剂和 C 1源具有双重作用,并且还可以用其氘代对应物 DMSO- d 6代替,从而能够掺入 -CD 2部分进入二芳基甲烷骨架。所开发的方法已应用于具有各种官能团的各种底物,该协议也已扩展到使用普通原料化合物合成抗乳腺癌剂和抗凝剂。此外,已通过对照实验明确证明了假设的机制。
Hydrogen bonding network-enabled Brønsted acid-catalyzed Friedel–Crafts reactions: a green approach to access unsymmetrical diaryl- and triarylmethanes
triarylmethanes are generally synthesized through metal-catalyzed cross-coupling or Friedel–Crafts arylation using multistep harsh reaction conditions with pre-functionalized starting materials. These reaction protocols use pyrophoric materials such as Grignard reagents, metal hydrides, and toxic, hazardous, and problematic solvents like benzene, DMF, and THF. This affects the reaction mass efficiency, and atom economy
不对称的二芳基和三芳基甲烷通常通过金属催化的交叉偶联或 Friedel-Crafts 芳基化合成,使用多步苛刻的反应条件和预官能化的起始材料。这些反应方案使用自燃材料,如格氏试剂、金属氢化物,以及有毒、有害和有问题的溶剂,如苯、DMF 和 THF。这会影响反应质量效率和原子经济性,并产生大量环境废物,从而导致高E因子。作为替代方案,本文使用廉价的市售 Brønsted 酸催化系统 ( p TSA·H 2O)/HFIP,我们描述了一种用于从可再生原料化学品合成不对称多芳基化烷烃的一锅三组分方法。与传统路线相比,我们避免使用任何自燃试剂、金属催化剂、有毒溶剂或格氏试剂,并报告了许多使用报告方法难以获得的示例。计算不同的绿色指标(原子经济性 (95%)、原子效率 (84.5%)、反应质量效率 (77.1%) 和E因子(1.26 kg kg −1没有溶剂回收的产品和 0.32 kg kg −1考虑
Synthesis and asymmetric anionic polymerization of substituted 7-aryl-2,6-dimethyl-1,4-benzoquinone methides
Substituted 7‐aryl‐2,6‐dimethyl‐1,4‐benzoquinone methides which have an electron‐donating methoxy substituent at the para‐position (p‐OMe, 2a) or an electron‐withdrawing chloro one at the para‐ (p‐Cl, 2b), meta‐ (m‐Cl, 2c), and ortho‐positions (o‐Cl, 2d) of the benzene ring were synthesized, and their asymmetricanionicpolymerizations using the complex of lithium 4‐isopropylphenoxide with (−)‐sparteine