2-arylbenzimidazolines (8), generated in situ from o-phenylenediamine (7) and the appropriate arylaldehydes, by reaction with 4-arylmethylenepyrazol-5-ones (1) or isoxazol-5-ones (2) produce the 4-arylmethylderivatives (3) or (4) and the C,C- (5) or the C,N-linkeddimers. The reaction was rationalised on the basis of the role of 2-arylbenzimidazoline as a reducing agent and proceeds by a non-chain
Organophosphane-Catalyzed Direct β-Acylation of 4-Arylidene Pyrazolones and 5-Arylidene Thiazolones with Acyl Chlorides
作者:Pankaj V. Khairnar、Yin-Hsiang Su、Yung-Chang Chen、Athukuri Edukondalu、Yi-Ru Chen、Wenwei Lin
DOI:10.1021/acs.orglett.0c02408
日期:2020.9.4
An efficient method for the direct β-acylation of arylidene pyrazolones and thiazolones with acyl chlorides in the presence of a base catalyzed by organophosphanes is reported. A variety of functionalized 4-arylidene pyrazolone and 5-arylidene thiazolonederivatives were prepared under metal-free and mild conditions via a tandem phospha-Michael addition/O-acylation/intramolecular cyclization/rearrangement
The thermal reaction between (E) or (Z)-pyrazolones (1) and 2,3-dimethylbutadiene (2) gave 1,2-dimethyl-5-arylcyclohexen-4-spiro-4' (1'-phenyl-3'-substituted-5'-pyrazolones) (3, 4), from a Diels-Alder reaction, and 4-aryl-2-isopropenyl-2-methyl-5-substituted-7-phenyldihydropyran [3,2-d] pyrazoles (5, 6), from a heterodiene reaction. The effect of the configuration of the starting pyrazolone, as well
The reaction of a series of (arylmethylene)azol-5-ones with phenacylpyridinium salt 3 in glacial acetic acid/ammonium acetate mixture gives different results depending on the starting azolone. The isoxazol-5-ones 1 give the unusual spirans 6 in a reaction cascade involving Michael- and retro-Michael reactions, C-alkylation, aldol addition, and diastereospecific cyclization. The reaction performed with oxazol-5-ones 11 has shown that a literature re po rt has to he corrected since no oxazolopyridines 12 hut rather arylideneimidazol-5-ones 13 are produced. In the case of pyrazolin-5-ones 14, the unavoidable formation of bis-adducts 15 always prevents any other type of reaction. (C) 2000 Elsevier Science Ltd. All rights reserved.
Regioselection inC-Bromo-N-phenylnitrilimine Cycloaddition to (Z)-4-(Arylmethylidene)azol-5-ones
The results of a study of the cycloaddition reaction of bromonitrilimine with (Z)-4-(arylmethylidene)isoxazol-5-ones and pyrazol-5-ones are reported. Spectroscopic and X-ray crystallographic data are presented to support structural assignments of the reaction products.