Oxidative Annulation of Anilides with Internal Alkynes Using an (Electron-Deficient ﾎｷ5-Cyclopentadienyl)Rhodium(III) Catalyst Under Ambient Conditions.
英文:
Oxidative Annulation of Anilides with Internal Alkynes Using an (Electron-Deficient ﾎｷ5-Cyclopentadienyl)Rhodium(III) Catalyst Under Ambient Conditions.
A dinuclear electron-deficient (ﾎｷ5-cyclopentadiene)rhodium(III) complex was synthesized on a preparative scale by a rhodium-catalyzed cross-[2+2+1]-cyclotrimerization of silylacetylene derivs. and alkyne esters, leading to substituted (silyl)fulvene derivs., followed by reductive complexation with rhodium(III) chloride in ethanol. The thus obtained dinuclear (electron-deficient ﾎｷ5-cyclopentadienyl)rhodium(III) complex is a highly active precatalyst for the oxidative annulation of anilides with internal alkynes under ambient conditions (at room temp. under air). A preference for annulation across electron-rich substrates over electron-deficient substrates was obsd. using this electron-deficient rhodium(III) complex (substituent effects). Under optimized conditions the synthesis of the target compds. was achieved using bis[(1,2,3,4,5-ﾎｷ)-1,3-bis(ethoxycarbonyl)-2,4,5-trimethyl-2,4-cyclopentadien-1-yl]di-ﾎｼ-chlorodichlorodirhodium as catalyst. The title compds. thus formed included 1-(5-chloro-2,3-diphenyl-1H-indol-1-yl)ethanone, 1-acetyl-2-phenyl-1H-indole-3-carboxylic acid Et ester, (3-cyclopropyl-2-phenyl-1H-indol-1-yl)ethanone, 1-(3-methyl-2-phenyl-1H-indol-1-yl)ethanone 1-(2,3-dipentyl-1H-indol-1-yl)ethanone and related substances, such as 1-acetyl-4,5-diphenyl-1H-pyrrole-2-carboxylic acid Me ester. 2,3,4-Triphenyl-1(2H)-isoquinolinone was also formed a byproduct. N-(Phenyl-2,3,4,5,6-d5)acetamide was also used as a starting material. [on SciFinder(R)]
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