2- cyano-substituted pyrroles synthesis

Another acceptor unit that has achieved high-performance D A copolymers with a number of donors is thieno[3,4-c]pyrrole-4,6-dione, called TPD. The synthesis of TPD can start with un-substituted thiophene, which can be converted into 3,4-dibromothiophene via selective debromination of the tetrabrominated thiophene. After the cyano substitution and hydrolysis, as-formed thiophene-3,4-dicarboxylie acid is brominated to provide the halogens... 

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-... 

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. 

Although the hydroxy group is a relatively poor leaving group, its base-catalyzed nucleophilic substitution by the mechanism shown in Scheme 69 accounts not only for the hydrogenolysis of the 3-hydroxymethylindoles, but also for their SN reactions with ethoxide ions, cyanide ions and with piperidine. Nucleophilic substitution on 2-hydroxymethyl-pyrroles is generally precluded by the faster formation of the bis(2-pyrrolyl)methanes, but the synthesis of 2-cyano-2-(2,5-dimethyl-3-pyrroIyl) propanes from 2,5-dimethylpyrrole, propanone and potassium cyanide probably results from an SN reaction of the cyanide ion upon the initially formed 3-pyrrolylcarbinol (81USP4248784). The formation of (294)... 

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