- Rhodium(III)-Catalyzed Selective Monoarylation of β or γ C(sp3)-H Bonds Assisted by a Trimethylpyrazole Group
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The selective arylation of unactivated β or challenging γ primary and secondary β-C(sp3)-H bonds has been developed with a Cp*Rh(III) catalyst assisted by a trimethylpyrazole group. A rarely reported six-membered rhodacycle has been identified in rhodium-catalyzed C(sp3)-H activation reactions. Preliminary mechanistic studies have revealed that a concerted metalation-deprotonation pathway might be involved in the C-H activation step.
- Yuan, Chunchen,Tu, Guangliang,Zhao, Yingsheng
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supporting information
p. 356 - 359
(2017/04/24)
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- AROMATIC NUCLEOPHILIC SUBSTITUTION REACTIONS OF ACTIVATED N-ARYLPYRAZOLES WITH FORMAMIDES
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Different activated N-arylpyrazoles, as N-(2',4'-dinitrophenyl)-3,5-dimethylpyrazole, N-picryl-3,5-dimethylpyrazole etc., can react with excess formamides, as formamide N-methylformamide and N,N-dimethylformamide, at 165-175 deg C, for 5-6 hours, resulting amines in high yieds.This reaction is influenced by steric hindrance.
- Chiriac, Constantin I.,Lupu, Viorel,Chiriac, Florentina,Ropot, Radu,Tibirna, Mihaela,Truscan, Ion
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p. 549 - 553
(2007/10/03)
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- A Study on the Reactions of some Ketenes with 1-Aroyl-1H-pyrazoles
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1-Aroyl-3,4,5-trimethyl-1H-pyrazoles (1a-c) react with diphenylketene (DPK) to afford the enol esters (2); this was confirmed by X-ray analysis.From the reaction of the pyrazoles (1) with dichloroketene (DCK) the pyrazolylpropanediones (3) are isolated, whereas from the reaction with dimethylketene (DMK) both the enol esters (2) and the pyrazolylpropanediones (3) were obtained.The hydrolysis of the products (3) was also studied.The corresponding pyrazolylpropanediones (10) and the enol esters (11) or their degradation products (12) were isolated from the reactions of the pyrazoles (1a-c) with some mixed anhydrides (9) in the presence of triethylamine.The structure of (10e) has also been confirmed by X-ray crystallography.Plausible schemes accounting for the formation of the products involving as a common step the quaternization of N-1 are envisaged.
- Mitkidou, Sophia,Papadopoulos, Stelios,Stephanidou-Stephanatou, Julia,Terzis, Aristides,Mentzafos, Demetrios
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p. 1025 - 1031
(2007/10/02)
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