Pyrroles 2-cyanomethyl

Annulation of the precursor 141 under basic conditions gave the fluorinated pyrrole derivative 142 (Equation 40) <1997BSF725>. Likewise, base-induced cyclization of A-(cyanomethyl)propargylamines has been shown to produce pyrroles in moderate yields <1995TL2823>. 

Several new routes involve formation of one carbon-carbon bond in pre-formed substrates. Palladium-catalyzed cyclization of /3-hydroxyenamine derivatives has been employed in a route to substituted pyrroles and 4,5,6,7-tetrahy-droindoles with multiple substituents by formation of the C-3-C-4 bond as the key feature, as illustrated by construction of the molecule 534 (Equation 146) <2006T8533>. Zinc perchlorate-catalyzed addition of alcohols to the nitrile functionality of a-cyanomethyl-/3-ketoesters, followed by annulation gave access to a series of substituted ethyl 5-alkoxypyrrole-3-carboxylates <2007T461>. Similar chemistry has also been used for synthesis of a related set of pyrrole-3-phosphonates <2007T4156>. A study on preparation of 3,5,7-functionalized indoles by Heck cyclization of suitable A-allyl substituted 2-haloanilines has also appeared <2006S3467>. In addition, indole-3-acetic acid derivatives have been prepared by base induced annulation of 2-aminocinnamic acid esters (available for instance from 2-iodoani-lines) <2006OL4473>. 

D-arablnofuranosyl-2-cyanomethyl-lH-pyrrole-3-carboxylate,° 3-benzoyloxy-l-3-D-ribofuranosyl-pyrazole-4-carboxyllc acid, l-(2,3,5-tri-0-benzoyl-3-D-ribofuranosyl) derivatives of tetrahydro-2H-1,3-diazepine-2,4(3H)-dione and 6,7-dihydro-2H-1,3-diazepine-2(3H)-one, cis-(5R,6R)-5,6-dlhydroxy-5,6-dlhydrothymldlne (a radiation product of thymidine), " 3 -azido-3 -deoxy-thymidlne, ... 

Evolution of large amount of nitriles in the thermal decomposition of polypyrroles is interesting because no nitriles evolve from pyrrole in the general thermal decomposition. Nitriles are thought to evolve from the main chain, including cyano(-C N), nitrilo (-N=), and/or cyanomethyl, the existence of which may be confirmed in the IR spectrum of polypyrroles. 

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