Investigations into the Kinetic Modeling of the Direct Alkylation of Benzylic Amines: Dissolution of K2CO3 Is Responsible for the Observation of an Induction Period
摘要:
Investigations into the kinetics of a Rh(I)-catalyzed direct C-H alkylation of benzylic amines with alkenes revealed that K2CO3, which is effectively insoluble in the reaction mixture, is only needed in the beginning of the reaction. During the concomitant induction period, K2CO3 is proposed to dissolve to a vanishingly small extent and the Rh-precatalyst irreversibly reacts with dissolved K2CO3 to form the active catalyst. The duration of this induction period is dependent on the molar loading, the specific surface, the H2O content of K2CO3, and agitation, and these dependences can be rationalized based on a detailed kinetic model.
it is possible to activate toluene efficiently and use it directly for the benzylation of different 2-aminopyridines. The transformation is not restricted to simple toluene, but also substituted derivatives give the desired product in good yields. Effective cleavage of the pyridine moiety is presented.
Within this contribution, the development and substrate scope evaluation of a direct alkylation protocol of the C(sp3)–H bond of benzylic aminesusing alkyl bromides is reported. This pyridine-directed method is initiated by elimination of the alkyl bromide to a terminal olefin, which is then the true alkylating agent. Graphical abstract
Quaternary Ammonium Salts as Alkylating Reagents in C–H Activation Chemistry
作者:Manuel Spettel、Robert Pollice、Michael Schnürch
DOI:10.1021/acs.orglett.7b01946
日期:2017.8.18
of benzylic amines via C(sp3)–H activation using quaternaryammoniumsalts as alkyl source is described. The reaction proceeds via in situ formation of an olefin via Hofmann elimination, which is the actual alkylating reagent. This represents an operationally simple method for substituting gaseous and liquid olefins with solid quaternaryammoniumsalts as alkylating reagents, which is transferable to
C(sp<sup>3</sup>)–H Bond Arylations Catalyzed by Well-Defined [Ru(O<sub>2</sub>CMes)<sub>2</sub>(<i>p</i>-cymene)]
作者:N. Y. Phani Kumar、Rajkumar Jeyachandran、Lutz Ackermann
DOI:10.1021/jo400658d
日期:2013.4.19
The well-characterized ruthenium(II) biscarboxylate complex [Ru(O2CMes)2(p-cymene)] enabled versatile direct (hetero)arylations of C(sp3)–H bonds with low (co)catalyst loading and ample substrate scope. Detailed mechanistic studies provided strong support for a facile and reversible C(sp3)–H bond metalation.
One-Pot Access to <i>peri</i>-Condensed Heterocycles via Manganese-Catalyzed Cascade C–N and C–C Bond Formation
作者:Yunliang Yu、Yadong Feng、Remi Chauvin、Shuangshuang Ma、Lianhui Wang、Xiuling Cui
DOI:10.1021/acs.orglett.8b01586
日期:2018.7.20
A Mn(III)-catalyzed three-component cascade C–H/N–H functionalization of 2-aminopyridines with 2 equiv of dialkyl butyndioates leads to peri-condensed tricylic azines through a selective, but partly destructive, stoichiometry. A wide range of 2,11-diazatricyclo[5.3.1.04,11]undeca-1(10),4,6,8-tetraen-3-ones were thus obtained with moderate to high yields in a step-economical fashion under mild conditions