Regioselective formation of 2,5-disubstituted oxazoles via copper(I)-catalyzed cycloaddition of acyl azides and 1-alkynes.
نویسندگان
چکیده
The reaction of 1-alkynes with acyl azides in the presence of [Tpm(*,Br)Cu(NCMe)]BF(4) [Tpm(*,Br) = tris(3,5-dimethyl-4-bromopyrazolyl)methane] as the catalyst provides 2,5-oxazoles in moderate to high yields. This is a novel transformation of the CuAAC type that constitutes a significant variation of the commonly observed [3 + 2] cycloaddition reaction to yield 1,2,3-triazoles.
منابع مشابه
Phosphoramidite accelerated copper(i)-catalyzed [3 + 2] cycloadditions of azides and alkynes.
Monodentate phosphoramidite ligands are used to accelerate the copper(i)-catalyzed 1,3-dipolar cycloaddition of azides and alkynes (CuAAC) rapidly yielding a wide variety of functionalized 1,4-disubstituted-1,2,3-triazoles; Cu(i) and Cu(ii) salts both function as the copper source in aqueous solution to provide excellent yields.
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Cp*RuCl(PPh3)2 is an effective catalyst for the regioselective "fusion" of organic azides and terminal alkynes, producing 1,5-disubstituted 1,2,3-triazoles. Internal alkynes also participate in this catalysis, resulting in fully substituted 1,2,3-triazoles.
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Tetrafluoroethylene-containing azides are accessed in two steps (one pot) from tetrafluoroalkyl bromides by metalation and reaction with electrophilic azides. Subsequent copper(i)-catalyzed azide-alkyne cycloaddition afforded N-tetrafluoroethyl and N-tetrafluoroethylene 4-substituted 1,2,3-triazoles. In addition, the protocol for the synthesis of 4,5-disubstituted 1,2,3-triazoles is presented.
متن کاملCopper(I)-catalyzed cycloaddition of silver acetylides and azides: incorporation of volatile acetylenes into the triazole core.
Silver acetylides and organic azides react under copper(I) catalysis to afford 1,4-disubstituted 1,2,3-triazoles. Mechanistic studies implicate a process involving transmetallation to copper acetylides prior to cycloaddition. This work demonstrates that silver acetylides serve as suitable precursors for entry into copper-mediated coupling reactions. This methodology allows the incorporation of ...
متن کاملRoom temperature copper(II)-catalyzed oxidative cyclization of enamides to 2,5-disubstituted oxazoles via vinylic C-H functionalization.
A copper(II)-catalyzed oxidative cyclization of enamides to oxazoles via vinylic C-H bond functionalization at room temperature is described. Various 2,5-disubstituted oxazoles bearing aryl, vinyl, alkyl, and heteroaryl substituents could be synthesized in moderate to high yields. This reaction protocol is complementary to our previously reported iodine-mediated cyclization of enamides to affor...
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ورودعنوان ژورنال:
- Journal of the American Chemical Society
دوره 133 2 شماره
صفحات -
تاریخ انتشار 2011