Pyrrole 2-cyano

Pyrrole, 2-cyano-l-(2-hydroxyethyl)-5-nitro-ipso substitution, 4, 243 Pyrrole, 2-cyano-l-methyl-photochemical rearrangement, 4, 42 photolysis, 4, 203 Pyrrole, 2-cyano-3-methyl-photochemical rearrangement, 4, 202 Pyrrole, 2-cyano-4-methyl-photochemical rearrangement, 4, 202 Pyrrole, 2-cyano-5-methyl-photochemical rearrangement, 4, 202 Pyrrole, diacetoxymethyl-synthesis, 4, 274 Pyrrole, 2,4-diacetyl-synthesis, 4, 218 Pyrrole, 2,5-diacetyl-synthesis, 4, 218, 219 Pyrrole, 2,4-dialkyl-... 

Mild acid converts it to the product and ethanol. With the higher temperatures required of the cyano compound [1003-52-7] (15), the intermediate cycloadduct is converted direcdy to the product by elimination of waste hydrogen cyanide. Often the reactions are mn with neat Hquid reagents having an excess of alkene as solvent. Polar solvents such as sulfolane and /V-m ethyl -pyrrol i don e are claimed to be superior for reactions of the ethoxy compound with butenediol (53). Organic acids, phenols, maleic acid derivatives, and inorganic bases are suggested as catalysts (51,52,54,59,61,62) (Fig. 6). 

Many other biologically active pyrroles have been prepared by this reaction. 3-Cyano-3,4-disubsdnited pyrroles are prepared by thereacdon ofisocyanoacetonitnie v/ithfi-nitro acetates. 

Fig. 37 Addition of phenols, 2-cyano-pyrrol, or hydrazoic acid to ketenes...

A more complex reaction is involved in the cooligomerization of acetylenes and tert-butyl isocyanide using nickel acetate as the catalyst (Scheme 20)43 the nature of intermediate complexes leading to the formation of 2-cyano-5-terf-butylaminopyrroles has not been established. Cocyclization of tert-butyl isocyanide with coordinated hexafluoro-2-butyne gives rise to coordinated cyclopentadienone anils for molybdenum systems,44 hence the nature of acetylene substitutents and of the organometallic catalyst play crucial roles in these processes. The pyrrole products from the former reaction can be decomposed by sulfuric acid and the overall sequence provides a simple synthesis of 5-amino-2-cyanopyrroles (Scheme 20). 

A facile synthesis of 5-substituted 3-aminopyrrole-2-carboxylates has been developed wherein condensation of diethyl aminomalonate with a-cyano ketones 46 was facilitated by prior formation of the p-toluenesulfonyl enol ether 47 <00JOC2603>. Addition of the amine component is followed by cyclization and decarboxylation to afford the pyrroles 48. 

The reactions of methyl 2-formyl-677 or 6-substituted furo[2,3-. ]pyrrole-5-carboxylates 31d-f or 154 <1997MOL69, 1999CCC1135> with malononitrile, methyl cyanoacetate, and 2-furylacetonitrile, respectively, afforded the corresponding methyl 2-(2,2-dicyanovinyl)-677- or 6-substituted furo[2,3-. ]pyrrole-5-carboxylates 294a-d, methyl 2-[2-cyano-2-(methoxycarbonyl)vinyl]-677- or 6-substituted furo[2,3-. ]pyrrole 5-carboxylates 295a-d, and methyl... 

As with other series involving the annulation of a pyrimidine ring onto a five-membered ring, the usual requirement is to have two adjacent functional groups, one of which is an amine. The use of a cyano group as the other functional group occupies the majority of examples in such syntheses. Therefore, it is not surprising that this situation holds in the syntheses of pyrrolo[2,3-,y pyrimidines from pyrroles. 

Likewise 3-amino-2-cyano-4-(3-methoxyphenyl)-A -carboethoxypyrrole is converted into 7-(3-methoxyphenyl)-pyrrolo[3,2- pyrimidin-4-one by, first decarboxylation, and then cyclization in refluxing formic acid <2006BMCL2091>. Replacing the 3-methoxyphenyl group on the pyrrole with a reduced pyrrole (a mimic of a ribofuranose ring) leads to a 4-aminopyrrolo[3,2- pyrimidine when treated with formamidine acetate <2006BMCL2662>. 

The PMR spectra of substituted derivatives, however, provide additional evidence for the structure of bridged [12]annulenes. A comparison of 92a and 92b reveals a normal control of the cyano group over the chemical shift of the neighboring protons (A = 1.0 ppm), the influence on the remote pyrrolic protons being small (A = 0.11-0.39 ppm). Hence diazapyracylenes should be composed of loosely connected closed-shell moieties (formula 97a) the influence of the substituents on the chemical shift being limited to the substituted part of the molecule.112... 

In methanolic cyanide, N-substituted pyrroles193 are substituted in the 2-position by a cyano group on anodic oxidation. Methoxylation, which is often observed as a side reaction in the anodic oxidation in methanolic cyanide, was suppressed completely. When N-substituted pyrroles carry a methyl group in the 2- and 5-positions, a side-chain cyanation occurs.193,194... 

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