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。
<i>tert</i>-Butyl nitrite mediated nitrogen transfer reactions: synthesis of benzotriazoles and azides at room temperature
A conversion of o-phenylenediamines into benzotriazoles was achieved at room temperature using tert-butyl nitrite. The optimized conditions are also well suited for the transformation of sulfonyl and acyl hydrazines into corresponding azides. This protocol does not require any catalyst or acidic medium. The desired products were obtained in excellent yields in a short span of time.
Pd/PC‐Phos‐Catalyzed Enantioselective Intermolecular Denitrogenative Cyclization of Benzotriazoles with Allenes and N‐Allenamides
作者:Pei‐Chao Zhang、Jie Han、Junliang Zhang
DOI:10.1002/anie.201904805
日期:2019.8.12
Reported herein is an asymmetric Pd/PC‐Phos‐catalyzeddenitrogenativecyclization of benzotriazoles with allenes and N‐allenamides, representing the first example of enantioselectivedenitrogenativecyclizations of benzotriazoles. A series of optically active 3‐methyleneindolines were obtained in good yields with high ee values. The use of inexpensive and readily available starting materials, high
Pd-Catalyzed denitrogenative functionalizations of benzotriazoles with alkenes and 1,3-dienes have been developed, which enable the rapid access of diverse ortho-amino styrenes and 2-vinylindolines, respectively. This study shows the great potential of benzotriazoles as a [1C]-synthon in cross-coupling reactions and an aza-[3C]-synthon in cycloaddition reactions.
4-benzotriazine derivates with good yield. This new protocol does not employ any transition metal reagent and enables the cycloaddition by cleavage of the N–N single bond. The use of inexpensive and readily available starting materials, a broad substrate scope, mild reaction conditions, metal-free, and versatile functionalization of the 1,2,4-benzotriazines make this strategy more attractive.