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。
Construction of functionalized 2,3-dihydro-1,4-benzoxazines via [5 + 1] annulations of 2-halo-1,3-dicarbonyl compounds with imines
A series of functionalized 2,3-dihydro-1,4-benzoxazines were obtained in moderate to excellent yields via domino [5 + 1] annulations of 2-halo-1,3-dicarbonyl compounds 2 with imines 1 under mild conditions and the application of this method in the synthesis of bioactive analogues, such as functionalized tetracyclic-1,4-benzoxazines which contain two new heterocyclic rings and one quaternary carbon
Mono- and Binuclear Zinc Complexes with a Bidentate Phenol-Containing 2-Benzylideneamino-5-Methylphenol Schiff Base
作者:N. A. Protasenko、S. V. Baryshnikova、T. V. Astaf’eva、A. V. Cherkasov、A. I. Poddel’sky
DOI:10.1134/s1070328421060038
日期:2021.6
Abstract The reaction of zinc chloride with 2-benzylideneamino-5-methylphenol (LH), a bidentate Schiff base, in 1 : 1 molar ratio in the presence of triethylamine gives the ionic complex [Et3NH]+[LZnCl2]– (I). The reaction between the zinc salt (chloride or acetate) and LH in 1 : 2 ratio results in complete displacement of the zinc salt anions to give bis-o-iminophenolate ZnL2 (II), which exists in
containing contiguous tertiary and quaternary stereogenic carbon centers were synthesized by using the title reaction. The reaction was catalyzed by a chiral N,N′‐dioxide scandium(III) complex under mild reaction conditions. Based on experimental investigations, a possible transition state has been proposed to explain the origin of asymmetric inductivity.
The chiral N,N′-dioxide–Yb(OTf)3 complex-catalyzed enantioselective aza-Diels–Alder reaction of Brassard’s diene with aldimines has been developed, giving the corresponding α,β-unsaturated δ-lactam derivatives in moderate yields with good enantioselectivities (up to 81% ee and up to 99% ee by single recrystallization) under mild conditions. Isolation of the reaction intermediate indicates that this