甲肟基团已成为多种 C-H 官能化的多功能导向基团。尽管甲肟作为一种强大的功能手柄很重要,但通常需要将甲肟转化为母酮,但通常需要苛刻且官能团不耐受的反应条件。因此,甲肟的应用及其随后在后期转化为相应的酮可能会出现问题。在这里,我们提出了一组替代条件,以使用光激发硝基芳烃实现甲肟到母酮的温和且官能团耐受的转化。该方法的实用性体现在其在头孢内酯 D 的全合成中的应用。此外,还提供了通过同位素标记研究以及反应副产物分析获得的这种转化的机制见解。
Catalyst-Controlled [3 + 2] and [4 + 2] Annulations of Oximes with Propargyl Alcohols: Divergent Access to Indenamines and Isoquinolines
作者:Wanchun Gong、Zhi Zhou、Jingjing Shi、Bo Wu、Biyun Huang、Wei Yi
DOI:10.1021/acs.orglett.7b03546
日期:2018.1.5
Rhodium(III)- and iridium(III)-catalyzedC–H activation of oximes and coupling with propargyl alcohols is discussed. Depending on the catalyst, the reaction pathway switched between [3 + 2] and [4 + 2] annulations, thus giving divergent access to indenamines and isoquinolines in a one-pot and atom-economical manner. The hydroxyl group in the tertiary propargyl alcohol substrate was found to be crucial
C(sp2)–H bond oxidation of oximes or azobenzenes with diverse carboxylic acids has been developed. In contrast to the previous catalytic systems, this protocol features mild conditions (close to room temperature for most cases) and a broad substrate scope (up to 64 examples), thus constituting a versatile method to directly prepare diverse O-aryl esters. Moreover, the superiority of the nitrate additive
A Rh-catalyzed intermolecular coupling of diazomalonates with arene C-H bonds is reported. The reaction is initiated by electrophilic C-H activation, which is followed by coupling of the arylrhodium(III) complex with the diazomalonate. In most cases, arenes with oximes, carboxylic acids, and amines as directing groups cross-couple with diazomalonates with excellent regioselectivities and functional
A highly para‐selective CAr−H difluoromethylation of ketoxime ethers under ruthenium catalysis has been developed. A wide variety of ketoxime ethers are compatible with the reaction, which leads to the corresponding para‐difluoromethylated products in moderate to good yield. A mechanistic study clearly showed that chelation‐assisted cycloruthenation is the key factor in the para selectivity of the
已经开发了在钌催化下酮肟醚的高度对位选择性C Ar -H二氟甲基化。各种各样的酮肟醚均可与该反应相容,从而以中等至良好的产率产生相应的对二氟甲基化产物。一项机理研究清楚地表明,螯合辅助的环化钌是影响酮肟醚二氟甲基化对位选择性的关键因素。使用密度泛函理论来获得对位选择性的理论理解。#
Novel One-Pot Synthesis of <i>N</i>-Alkyl Arylamines from Oxime Ethers Using Organometallic Reagents
作者:Takeaki Naito、Partha Mukhopadhyay、Okiko Miyata
DOI:10.1055/s-2007-980358
日期:2007.6
α-disubstituted secondary arylamines from oxime ethers has been developed by two separate additions of organometallicreagents. As a related arylamine construction, very efficient synthesis of N-(diallyl)methyl arylamines is achieved via domino reactions involving addition-eliminative re-arrangement-addition reactions of acyclic and cyclic oxime ethers with allylmagnesium bromide.