117531-28-9Relevant articles and documents
Synthesis of 3-alkylbenzoxazolones from N-alkyl-N-arylhydroxylamines by contiguous O-trichloroacetylation, trichloroacetoxy ortho-shift, and cyclization sequence
Ram, Ram N.,Soni, Vineet Kumar
, p. 11935 - 11947 (2014/01/06)
Benzoxazolone pharmacophore is present in clinical pharmaceuticals, drug candidates, and many compounds having a wide spectrum of biological activities. The methods available for the synthesis of benzoxazolones have limited diversity due to problems in accessibility and air-sensitivity of diversely substituted o-aminophenols from which they are generally prepared by cyclocarbonylation with phosgene or its equivalents. The present paper describes a mild method for the synthesis of 3-alkylbenzoxazolones from easily accessible and air-stable nitroarenes. Nitroarenes were converted to N-alkyl-N-arylhydroxylamines in two steps involving partial reduction to arylhydroxylamines followed by selective N-alkylation. Treatment of N-alkyl-N-arylhydroxylamines with trichloroacetyl chloride and triethylamine afforded 3-alkylbenzoxazolones generally in good yields through an uninterrupted three-step sequence involving O-trichloroacetylation, N→Cortho trichloroacetoxy shift, and cyclization in a single pot at ambient temperatures. The present method is mild, wide in scope, economical, and regioselective. Many sensitive groups like alkyl and aryl esters, amide, cyano, and the carbon-carbon double bond survive the reaction.
N-Allylhydroxylamines from 1,2-Addition of Allyl Grignard Reagents to Nitro Compounds: Generality and Drawbacks of the Reaction
Barboni, Luciano,Bartoli, Giuseppe,Marcantoni, Enrico,Petrini, Marino,Dalpozzo, Renato
, p. 2133 - 2138 (2007/10/02)
Allyl Grignard reagents react with both aromatic and aliphatic nitro derivatives via 1,2-addition to the nitro group.Conversely, nitroalkanes give either intractable mixtures or exclusively 1,4-conjugate addition.Nitroarenes with high steric hindrance at the ortho position and low aromatic stabilisation give competive or exclusive conjugate addition at the reactive para position.The 'in situ' treatment of the unstable 1,2-adducts with aluminium hydrides in the presence of catalytic amounts of palladium on charcoal provides a general method of synthesis ofN-allylhydroxylamines.LiAlH4 is a very efficient reducing agent, but, in some cases, it does not allow the reduction to be stopped at the hydroxylamino stage.Red-Al and DIBAL-H are less efficient but they ensure greater selectivity.Red-Al avoids the complete reduction to amines except when a strongly electron-donating substituent such as a methoxy group is present in the para position of the aromatic ring.Hydroxylamines can be obtained by reaction of nitrosoarenes followed by aqueous quenching.However, this alternative reaction does not offer any improvement, since relevant amounts of azo and azoxy derivatives are recovered as by-products.
PALLADIUM(0)-CATALYZED HYDROXYLAMINATION OF ALLYL ESTERS. SYNTHESIS OF N-ALLYLHYDROXYLAMINES AND SECONDARY ALLYLAMINES
Murahashi, Shun-Ichi,Imada, Yasushi,Taniguchi, Yuki,Kodera, Yoichi
, p. 2973 - 2976 (2007/10/02)
Palladium-catalyzed reaction of allyl esters with hydroxylamines gives N-allylhydroxylamines, which are readily converted into secondary allylamines upon treatment with zinc powder in a dilute HCl solution.
