an efficient asymmetric denitrogenative cycloaddition of benzotriazoles with cyclic and acyclic 1,3-dienes enabled by Pd and chiral sulfonamide phosphine ligand. A variety of substituted hexahydrocarbazoles and indolines were delivered in good yields with high ee values. Interestingly, a pair of enantiomers could be obtained with the use of Xu1 and PC2 with the same absolute configuration. The synthetic
不对称脱氮环加成已成为构建手性氮杂杂环的有力工具。然而,迄今为止,仅探索了苯并三唑与不饱和烃的不对称脱氮环加成的一个例子,因为苯并三唑开环生成α-亚氨基金属类卡宾是一种热力学不利的过程。我们在此报告了由 Pd 和手性磺酰胺膦配体实现的苯并三唑与环状和非环状 1,3-二烯的有效不对称脱氮环加成反应。各种取代的六氢咔唑和二氢吲哚均以良好的收率和高 ee 值交付。有趣的是,使用Xu1和PC2可以获得一对对映异构体具有相同的绝对配置。还展示了光学活性六氢咔唑的合成效用。
Synthesis of (Difluoromethyl)cycloalkenes from 2‐Cycloalkenones by Utilizing Phospha‐Brook Rearrangement
Difluoromethyl‐substituted allylicphosphates were synthesized from 2‐cycloalkenones through the addition of a (difluoromethyl)phosphonate and subsequent phospha‐Brook rearrangement. The obtained allylicphosphates were converted to the corresponding difluoromethyl‐substituted cycloalkenes using the Cu‐mediated SN2’ reaction of Grignard or organolithium reagents.
通过添加(二氟甲基)膦酸酯和随后的Pha-Brook重排,由2-环烯酮合成二氟甲基取代的烯丙基磷酸酯。使用格氏试剂或有机锂试剂的Cu介导的S N 2'反应,将获得的烯丙基磷酸酯转化为相应的二氟甲基取代的环烯烃。
Resonance Effects in the Solvolysis of<i>α</i>-<i>t</i>-Butyl-<i>α</i>-neopentylbenzyl and<i>α</i>-<i>t</i>-Butyl-<i>α</i>-isopropylbenzyl<i>p</i>-Nitrobenzoates
Substituent effects on the solvolysis rates of α-t-butyl-α-neopentylbenzyl and α-t-butyl-α-isopropylbenzyl p-nitrobenzoates in 50% (v/v) aqueous EtOH at 75 °C were correlated with the Yukawa–Tsuno equation to give ρ = −3.37 and r = 0.78, and ρ = −3.09 and r = 0.68, respectively. The reduction in r values from r = 1.00 characteristic of full conjugation is ascribed to deviation from coplanarity of the
A highly stereoselective preparation of CF3-substituted 1-aryl-1,2-diphenylethenes: application to the synthesis of panomifene
作者:Myong Sang Kim、In Howa Jeong
DOI:10.1016/j.tetlet.2005.03.117
日期:2005.5
sulfide 3a was prepared stereoselectively in 77% yield from the reaction of 2 with phenyllithium at room temperature for 5 h. Oxidation of 3a with MCPBA afforded the corresponding vinyl sulfone 4a, in which (E)-4a can be crystallized in a mixture of CH2Cl2 and hexane. The addition–elimination reaction of (E)-4a with phenyllithium having substituents on the benzene ring provided 5a–j in 51–82% yields stereospecifically
Highly Diastereoselective Conjugate Addition of Aryllithium to Chiral β-Nitrostyrene Derivative: An Application to the Asymmetric Synthesis of 4-Aryl-1,2,3,4-tetrahydroisoquinoline
Highlydiastereoselectiveconjugateaddition of aryllithium to β-nitrostyrene derivative, having chiral acetal moiety derived from (S,S)-1,2-bis(1-hydroxypropyl)benzene, was achieved. The adduct wa...