We have developed a copper/manganese-mediated oxidative rearrangement of benzylamines to 4H-3,1-benzoxazines of potent interest in medicinal applications. The reaction proceeds uniquely through the initial copper/manganese-promoted intramolecular C-H amination giving benzazetidine intermediates and subsequent 4n electrocyclic ring opening/6 pi electrocyclic ring closing cascade. The key to success is the introduction of picolinamide-based N,N-bidentate directing group. The obtained benzoxazines can also be readily hydrolyzed to the corresponding 2-aminobenzyl alcohols, thus indicating that the overall transformations is regarded as the ortho-aminative rearrangement of benzylarnines to benzylic alcohols.
Selective catalytic Hofmann N-alkylation of poor nucleophilic amines and amides with catalytic amounts of alkyl halides
作者:Qing Xu、Huamei Xie、Er-Lei Zhang、Xiantao Ma、Jianhui Chen、Xiao-Chun Yu、Huan Li
DOI:10.1039/c6gc00938g
日期:——
A selective Hofmann N-alkylation reaction of amines/amides catalytic in alkylhalides is achieved by using alcohols as the alkylating reagents, affording mono- or di-alkylated amines/amides in high selectivities.
Manganese/cobalt-catalyzed oxidative C(sp<sup>3</sup>)–H/C(sp<sup>3</sup>)–H coupling: a route to α-tertiary β-arylethylamines
作者:Meiling Tan、Kaizhi Li、Jiangliang Yin、Jingsong You
DOI:10.1039/c7cc08512e
日期:——
An oxidative coupling reaction of an α-C(sp3)–H bond of amine with a benzylic C(sp3)–H bond provides diverse collections of α-tertiary β-arylethylamines.
A cobalt(II)-catalyzed regioselective aryl C–H bond oxygenation between arenes and aryl or aliphatic carboxylic acids under bidendate-chelation assistance is developed. This method provides an efficient approach to acyoxy-substituted arenes with a broad range of functional group tolerance. Furthermore, this reaction system could be further applied to the preparation of polyfunctional naphthylenes.
Cobalt-Catalyzed Selective Synthesis of Isoquinolines Using Picolinamide as a Traceless Directing Group
作者:Changsheng Kuai、Lianhui Wang、Bobin Li、Zhenhui Yang、Xiuling Cui
DOI:10.1021/acs.orglett.7b00702
日期:2017.4.21
first been employed as a traceless directing group for the cobalt-catalyzed oxidative annulation of benzylamides with alkynes to synthesize isoquinolines throughC–H/N–H bonds activation. Oxygen is used as a terminal oxidant. This protocol exhibits good functional group tolerance and excellent regioselectivity. Both terminal and internalalkynes can be efficiently applied to this catalytic system as substrates
Traceless Directing Group Assisted Cobalt-Catalyzed C−H Carbonylation of Benzylamines
作者:Fei Ling、Chongren Ai、Yaping Lv、Weihui Zhong
DOI:10.1002/adsc.201700780
日期:2017.11.10
The first example of cobalt‐catalyzed C(sp2)−H carbonylation of benzylamines using a traceless directing group is reported, which was successfully applied to the synthesis of N−unprotected iso‐indolinones through direct C−H/N−H bonds activation. This protocol tolerates a variety of functional groups and provides a facile and efficient method for the formal synthesis of (+)‐garenoxacin.
报道了使用无痕导向基团的钴催化苄胺的C(sp 2)-H羰基羰基化的第一个实例,该实例已成功地用于通过直接CH / H / NH键活化而合成N-未保护的异吲哚啉酮。该方案可耐受多种官能团,并为(+)-加仑沙星的正式合成提供了一种简便而有效的方法。