- N -Methylation of ortho -substituted aromatic amines with methanol catalyzed by 2-arylbenzo [d] oxazole NHC-Ir(iii) complexes
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Seven new chelated cyclometalated Ir complexes of ABON,P, ABON,O, and ABON,C(carbene) based on a rigid and tunable 2-arylbenzo[d]oxazole backbone have been prepared for the N-methylation of amines. Among these three coordinated modes, ABON,C(carbene)-chelated iridium-based catalysts exhibited good performance in the monomethylation of aromatic amines with methanol (MeOH) as the green methylation reagent. The steric-modified synthesis of ABON,C(carbene) complexes was described. The most active ABON,C(carbene) complex with marginal steric hindrance as a catalyst was obtained from the benzoxazole ring without a substituent and methyl group of the benzimidazole ring on the N-heterocyclic carbene (NHC) ligand. A variety of amines including para- and meta-substituted aromatic amines, as well as heterocyclic amines, were formulated as suitable substrates. Importantly, this catalyst considerably promoted the yield of the N-methylation of ortho-substituted aromatic amines. Controlled kinetic experiments and deuterium-labeling reactions of these ortho-substituted amines were conducted under optimized conditions. On the basis of the experimental results, a plausible mechanism was proposed.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhou, Quan,Lin, Yue-Jian,Hou, Xiu-Feng
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p. 5072 - 5082
(2019/04/17)
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- Gold-Catalyzed Cascade Cyclization of 2-Alkynyl-N-Propargylanilines by Rearrangement of a Propargyl Group
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Gold catalysis enables direct construction of tetracyclic fused indolines through the migration of a propargyl substituent from an aniline nitrogen atom to the C3-position of an indole from 2-alkynyl-N-propargylanilines. This reaction provides rapid access to fused three-dimensional indolines in a single operation with the formation of four bonds and three rings.
- Tokimizu, Yusuke,Oishi, Shinya,Fujii, Nobutaka,Ohno, Hiroaki
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supporting information
p. 7862 - 7866
(2015/06/30)
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- Radical cyclization approach to spirocyclohexadienones
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(Chemical Equation Presented) Cyclization of an aryl radical at the ipso position of a p-O-aryl-substituted acetamide or benzamide generates oxindoles or quinolones bearing spirocyclohexadienone rings. This versatile reaction is applied to formal synthese
- Gonzalez-Lopez De Turiso, Felix,Curran, Dennis P.
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p. 151 - 154
(2007/10/03)
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