Pyrrole-2-carboxaldehydes Oxidation

Pyrrole-2-carboxylic acid esters have been prepared from ethyl chloroformate and pyrrolylmagnesium bromide1 2 or pyrrolyllithium,3 by hydrolysis and decarboxylation of dimethyl pyrrole-1,2-dicarboxylate followed by re-esterification of the 2-acid4 and by oxidation of pyrrole-2-carboxaldehyde followed by esterification with diazomethane.4... 

Yanagimoto el a/.458 examined the antioxidative activity of heterocyclic MRPs in inhibiting the oxidation of hexanal by air. Of the three pyrroles, three furans, two thi-azoles, three thiophenes, and two pyrazines tested, pyrrole-2-carboxaldehyde was by far the most active, closely parallelling BHT in giving about 100% inhibition at 50 fig mL 1 and about 90% at 5 fig ml.. ... 

Although the 2,3,4,6-tetrahydro-l,l -methylene-2,2 -pyrromethen-5[l-//]-one (190) is not strictly a perhydropyrrolo[l,2-c]pyrimidine, it carries the essential features of this ring system. Synthesis was effected by treatment of pyrrole-2-carboxaldehyde (186) with diiodomethane in the presence of a base to give 187 which was oxidized to 188 by w-chloroper-benzoic acid. Intramolecular condensation of 188 gave 189 which was... 

Irradiation of 3-methylthiophene in hexafluoropropan-2-ol with added methanesulfonic acid brings about single electron-transfer oxidation and this yields a species that has been identified as the Z>w-protonated radical-cation of (289). Irradiation of 2-acetyl-5-iodothiophene leads to cleavage of the C-I bond and the resultant radical adds to acrylonitrile to afford the adduct (290) in moderate yield. Reactions of this type have also been described for iodofuran and iodopyrrole derivatives and in the latter case 4,5-diiodo-l//-pyrrole-2-carboxaldehyde reacts photochemically with thiophene to give... 

The reaction of l-amino-l-deoxy-n-fructose with 2,4-pentanedione gives 3-acetyl-2-methyl-4-(D-araZ)mo-tetrahydroxybutyl)pyrrole (20). Acetylation of this compound yields a tetra-O-acetyl derivative, and periodate oxidation of (20) furnishes 4-acetyl-5-methylpyrrole-3-carboxaldehyde (24), which can be subsequently oxidized to 4-acetyl-5-methylpyrrole-3-carboxylic acid (26). 

Some of these reactions give high yields of products, and are of interest from the preparative point of view. Pyrrole-2-carboxaldehydes, pyrrole-3-carboxaldehydes, and their corresponding acids are readily obtained in the oxidation of the (tetrahydroxybutyl)pyrroles. The aldol reactions may provide a convenient route to branched-chain, higher-carbon sugars. 

Thiocarbamoylthymidine has been converted into various species with heterocycles joined to thymidine through an ether link. Water-soluble C-linked nucleoside-porphyrins have been made by reaction of 2, 3 -0-iso-propylideneuridine-5 -carboxaldehyde with pyrrole to give a dipyrromethane, which was treated with p-fluorobenzaldehyde to give after oxidation a porphyrin... 

Many substituted thiophenes are commercially available. Thus, the study of the effects of substituents on polythiophene is relatively straightforward in comparison with pyrrole, whose 3-monosubstituted and 3,4-substituted derivatives are not easily synthesized. Table 3 gives many substituted thiophenes that can be electrochemi-cally oxidized to produce conducting polymers. Some derivatives, such as 3-thiophene acetic acid, 3-thiophene malonic acid, 3-thiophene carboxylic acid, and 3-thiophene carboxaldehyde do not polymerize at all [205). 

Benzodiazepine 1-Oxide, in B-80020 3//-1,2-Benzodiazepine 2-Oxide, in B-80020 2,2 -Bi-1 //-pyrrole-5-carboxaldehyde, B-80130 AT-Hydroxy-4-quinolinamine, H-80253... 

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