Imidoyl carbons

To date, palladium migration to vinylic positions remains unknown. Thus, palladium migration to sp2 carbons has been largely limited to aryl carbons. However, in addition to vinylic and aryl carbons, aldehydic and imidoyl carbons also possess sp2 hybridization and carry a C-H bond. This special type of sp2 C-H bond has also been subjected to palladium migration studies and preliminary success has been achieved. Currently, aryl to imidoyl [27] and aryl/alkyl to acyl [72] palladium migrations are known. Migrations from other types of carbons to imidoyl and acyl positions are... 

Conversion of CA into cyanuric chloride [108-77-0] (C1CN)3 by PCl is another example of reaction at carbon (78). Cyanuric chloride as an imidoyl chloride reacts as an acid chloride, unlike chloroisocyanurates. 

O-Acylated or mesylated oximes such as the ethyl carbonate of acetophenone-oxime 1772 react with TIS 17, with Beckmann rearrangement to the imidoyl iodide 1773, which adds phenylmagnesium bromide in situ to give 61% of the sec-... 

Trialkylsilyl radicals add to alkyl isocyanate to form imidoyl radicals 56 (Reaction 5.38). Detailed EPR studies established intermediates 56 to be strongly bent at the carbon bearing the unpaired electron [76], The absolute rate constant for the reaction of Et3Si radical with ieri-butyl isocyanate was found to be 5.5 x 10 s at 27 °C [13], whereas the relative rate of the addition of MesSi radicals to alkyl isocyanates was found to decrease in the... 

Grignard reagents and other carbon nucleophiles can react with imidoyl halides 438 to produce imines 439 (equation 186). Other nucleophiles may be used to displace successfully the halide. 

Heteropolyacids Hi4[NaPsW29MoOno] and H3PMO12O4 have been shown to be efficient catalysts for consecutive condensation of aldehydes with 5-aminopyrazole -carboxamide and cyclization into pyrazolo[3,4-t4pyrimidines <2007MI1467>. The reaction of ethyl 5-acylaminopyrazoles with hexachloroethane and triphenylphosphine in the presence of a base has been recently reported to afford an imidoyl chloride that reacted in situ with ethylamine yielding an amidine in 71% yield that cyclized readily in DMF in the presence of potassium carbonate to yield pyrazolopyrimidines in 65% yield <2007TL3983>. 

Imidoyl radicals are often prepared by the addition of carbon- or heteroatom-centred radicals to isocyanides, but can also be prepared by hydrogen atom abstraction from imines. This latter method has been adopted in a new annulation approach to quinoline synthesis. Thus, reaction of the imine 1 with phenylacetylene and di-isopropyl peroxydicarbonate in benzene at 60°C gave a mixture of the quinolines 2 and 3 in 65% yield (2 3 = 4.4). 

Difluoromethyl-Substituted Imines, Imidoyl Chlorides, and Nitrones. These CF2H nitrogen-bound building blocks have received much recent interest. A few examples are given in Scheme 4.34, along with their fluorine, proton, and carbon NMR spectral data. 

S-[N-(2,5-Dich lor-phenyl)-methoxy-carbon-imidoyl]- -0,0-diethylester XII/2, 824 -S-[3-(3,4-dich lor-phenyl)-l-methyl-ureidoester)-O.O-diisopropylester E2, 726 -S-(2,5-dichlor-phenylthiomethylester)-0,0-di-ethylester XII/2, 701... 

Imidoyl iodides. Reaction of oxime mesylates (or carbonates) of ketones with (C2H5)2A11 effects Beckmann rearrangement to imidoyl iodides, which can be directly alkylated with Grignard reagents and then reduced (DIBAH) to a-alkylated amines. Examples ... 

Carbodiimides are a unique class of reactive organic compounds having the heterocumu-lene structure R—N=C=N—R. They can be formally considered to be the diimides of carbon dioxide or the anhydrides of 1,3-substituted ureas, and they are closely related to the monoimides of carbon dioxide, the isocyanates. The substituent R can be alkyl, aryl, acyl, aroyl, imidoyl or sulfonyl, but nitrogen, silicon, phosphorous and metal substituted carbodiimides are also known. The unsubstituted carbodiimide HN=C=NH is isomeric with cyanamide, H2NCN. Mono substituted carbodiimides, generated in the thermolysis of 1-substituted tetrazoles, can be isolated at liquid nitrogen temperature but isomerize to the cyanamides at higher temperatures. ... 

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