- Oxime-mediated facile access to 5-methylisoxazoles and applications in the synthesis of valdecoxib and oxacillin
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A palladium-catalyzed efficient synthesis of 5-methylisoxazoles via oxime-mediated functionalization of unactivated olefins is described. The reaction affords a variety of 5-methylisoxazoles in moderate to good yields. To further demonstrate the utility of the method, the rapid synthesis of valdecoxib and oxacillin is reported. (Chemical Equation Presented).
- Dong, Kui-Yong,Qin, Hai-Tao,Bao, Xing-Xing,Liu, Feng,Zhu, Chen
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p. 5266 - 5268
(2015/01/09)
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- Pd(0)-catalyzed decarboxylative coupling and tandem C-H arylation/decarboxylation for the synthesis of heteroaromatic biaryls
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An effective Pd(0) carbene complex was successfully employed in the decarboxylative coupling of the heteroaromatic carboxylic acids (imidazo[1,2-a]pyridine and isoxazole) with aryl halides. For carboxyindoles, either decarboxylative coupling or tandem C-H arylation and decarboxylation occurred, leading to the formation of C2-monoarylated indoles.
- Nandi, Debkumar,Jhou, Yang-Ming,Lee, Jhen-Yi,Kuo, Bing-Chiuan,Liu, Chien-Yu,Huang, Pei-Wen,Lee, Hon Man
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p. 9384 - 9390
(2013/01/15)
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- Reaction of allenylmagnesium and allenylindium bromides with nitrile oxides: synthesis of novel 5-butynyl- and 5-methylisoxazoles
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5-Butynylisoxazoles were obtained in high yields through a domino addition, C-O heterocyclization involving allenylmagnesium bromide and benzonitrile oxide in dry THF, in which the corresponding 5-methylisoxazoles were isolated in trace amounts. However, when the reactions were attempted in aqueous media using allenylindium bromide, 5-methylisoxazoles were formed as the sole products in high yields.
- Sampath Kumar,Singh, Parvinder Pal,Shafi, Syed,Reddy, Pitta Bhaskar,Shravankumar, Kankala,Reddy, Doma Mahender
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p. 887 - 890
(2007/10/03)
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- Preparation of isoxazol(in)yl substituted selenides and their further deselenenylation reaction to synthesize 3,5-disubstituted isoxazoles
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We report a mild 1,3-dipolar cycloaddition protocol for the preparation of 3-aryl-5-phenylselenomethyl isoxazoles and isoxazolines regioselectively. The former was further reacted with LDA and electrophilic substrates followed by selenoxide syn-eliminatio
- Xu, Wei Ming,Tang,Huang, Xian
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p. 501 - 506
(2007/10/03)
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- Convenient Approach to 3,4-Diarylisoxazoles Based on the Suzuki Cross-Coupling Reaction
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The Suzuki cross-coupling reaction was found effective for rapid access to a series of 3,4-diarylisoxazoles of pharmacological interest. The efficiency of this approach was demonstrated by the synthesis of the highly potent COX-2-selective inhibitor, 4-(5-methyl-3-phenyl-4-isoxazolyl)benzenesulfonamide (valdecoxib), and its analogues. Thus, the coupling reaction between (3-aryl-5-methyl-4-isoxazolyl)boronic acids, prepared in situ from the corresponding bromides using triisopropyl borate, and aryl bromides containing a 4-sulfonamide or 4-methylsulfonyl group under the standard conditions [Pd(PPh3)4, Na2CO3, EtOH-H2O, reflux] yielded the target 3,4-diarylisoxazoles in good yields.
- Dileep Kumar,Ho, ManKit M.,Leung, Jennifer M.,Toyokuni, Tatsushi
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p. 1146 - 1151
(2007/10/03)
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