Mechanism of Cobalt(II) Porphyrin-Catalyzed C–H Amination with Organic Azides: Radical Nature and H-Atom Abstraction Ability of the Key Cobalt(III)–Nitrene Intermediates
作者:Volodymyr Lyaskovskyy、Alma I. Olivos Suarez、Hongjian Lu、Huiling Jiang、X. Peter Zhang、Bas de Bruin
DOI:10.1021/ja204800a
日期:2011.8.10
cobalt(III)-amido complexes (por)Co(III)-NHY (R'(•)···(por)Co(III)-NHY}). These close-contact pairs readily collapse in a virtually barrierless fashion (via transition state TS3) to produce the cobalt(II)-amine complexes (por)Co(II)-NHYR', which dissociate to afford the desired amine products NHYR' (6) with regeneration of the (por)Co catalyst. Alternatively, the close-contact pairs R'(•)···(por)Co(III)-NHY}
3. leads to amide products which can be hydrolyzed under mild conditions. The amidation reaction is mild, general and compatible with both primary C−H bonds of tertiary and secondary alcohols, as well as secondary C−H bonds of cyclic secondary alcohols. This method provides an easy access to free 1,2-aminoalcohols after efficient and mild cleavage of the oxime directing group and activated amide.
申请人:The Board of Trustees of the University of Illinois
公开号:US20190106448A1
公开(公告)日:2019-04-11
Reactions that directly install nitrogen into C—H bonds of complex molecules are significant because of their potential to change the chemical and biological properties of a given compound. Selective intramolecular C—H amination reactions that achieve high levels of reactivity, while maintaining excellent site-selectivity and functional-group tolerance is a challenging problem. Herein is reported a manganese perchlorophthalocyanine catalyst [Mn
III
(ClPc)] for intermolecular benzylic C—H amination of bioactive molecules and natural products that proceeds with unprecedented levels of reactivity and site-selectivity. In the presence of Brønsted or Lewis acid, the [Mn
III
(ClPc)]-catalyzed C—H amination demonstrates unique tolerance for tertiary amine, pyridine and benzimidazole functionalities. Mechanistic studies indicate that C—H amination proceeds through an electrophilic metallonitrene intermediate via a stepwise pathway where C—H cleavage is the rate-determining step of the reaction. Collectively these mechanistic features contrast previous base-metal catalyzed C—H aminations.
Cobalt(II)-Catalyzed Intermolecular Benzylic C−H Amination with 2,2,2-Trichloroethoxycarbonyl Azide (TrocN<sub>3</sub>)
作者:Hongjian Lu、Velusamy Subbarayan、Jingran Tao、X. Peter Zhang
DOI:10.1021/om900916g
日期:2010.1.25
2,2,2-Trichloroethoxycarbonyl azide (TrocN3) is an effective nitrene source for cobalt(II)-catalyzedintermolecular nitrene insertion of C−H bonds. Among different metalloporphyrins studied, Co(II)(TPP) was shown to be a competent catalyst for the selective amination of various benzylic C−H bonds under mild conditions without the need of other reagents or additives, forming the desired Troc-protected
[RuIV(F20-TPP)Cl2] efficiently catalysed inter- and intra-molecular nitrene insertion into sp3 C–H bonds of hydrocarbons using phosphoryl azides as nitrene sources
作者:Wenbo Xiao、Jinhu Wei、Cong-Ying Zhou、Chi-Ming Che
DOI:10.1039/c3cc41110a
日期:——
[Ru(IV)(F20-TPP)Cl2][H2(F20-TPP) = meso-tetrakis(pentafluorophenyl)porphyrin] is an active catalyst for both inter- and intra-molecular nitreneinsertion into sp(3) C-H bonds of hydrocarbons in good to high product yields using phosphoryl azides as nitrene sources.