Benzyl pyrrole-2-carboxylate

The related planar pyrrole analog 118 has also been prepared (2) from either ethyl or benzyl pyrrole-2-carboxylate 116. Direct alkylation with diethyl phosphonomethyl triflate (70) and base produced the N-phosphonomethylpyrrole 2-carboxylate 117, which was deprotected with trimethylsilyl bromide and saponified to the corresponding phosphonic acid 118. 

Several new examples of the Barton-Zard pyrrole synthesis from nitroalkenes and isocyanoacetate esters demonstrate the broad utility of this procedure. An excellent yield of ethyl 3-(9-anthryl)-4-ethylpyrrole-2-carboxylate was obtained starting with the nitroalkene from anthracene-9-carboxaldehyde and 1-nitropropane. <95TL8457> Bums et.al. reported an improved synthesis of benzyl isocyanoacetate which facilitates the synthesis of benzyl pyrrole-2-carboxylate esters by this method. <95SC379> 3-(l-Arylpyrrol-2-yl)pyrrole-2-carboxylates were prepared from l-aryl-2-(nitrovinyl)pyrroles. <95JHC 1703>... 

Ono, N., Katayama, H., Nisyiyama, S., Ogawa, T. Regioselective synthesis of 5-unsubstituted benzyl pyrrole-2-carboxylates from benzyl isocyanoacetate. J. Heterocycl. Chem. 1994, 31,707-710. 

Pyrrole-2-carboxamide, N,N-dimethyl-conformation, 4, 194 Pyrrole-3-carboxamide, N,N-dimethyl-conformation, 4, 194 Pyrrolecarboxamides synthesis, 4, 242 Pyrrole-2-carboxamides synthesis, 4, 148, 360 Pyrrolecarboxylhydrazides Curtius degradation, 4, 362 Pyrrole-2-carboxylic acid, l-benzyl-3-hydroxy-ethyl ester... 

Benzyl isocyanoacetate is a nsefnl reagent for the preparadon of benzyl 5-nnsnbsdnited pyrrole-2-carboxylates, which are widely used In the synthesis of porphyrins." Ono and coworkers have prepared pyrroles snbsdnited with various snbsdnients at the fi-posidons."" Because the reqidsite fi-nitro acetates for nitroalkenesi are readily available by the Henry... 

The synthesis is straightforward because for the preparation of the tetrapyrranc a bipyrrole can also be used as a central unit to which a benzyl 5-(acetoxymethyl)pyrrole-2-carboxylate can be attached as the terminal pyrrole rings. Debenzylation by catalytic hydrogenation then gives the desired tetrapyrrane building block 68. 

Phase-transfer catalysis was found <1996CHEC-II(7)1> to be successful for N-substitution of the furo[3,2-/ ]pyrrole system. The reaction of 81a with methyl iodide or benzyl chloride gave 81b and 81c derivatives. Methyl 4-acetyl-2-[3-(trifluoromethyl)phenyl]furo[3,2-3]pyrrole-5-carboxylate 82 was obtained by reacting 81a in boiling acetic anhydride (Scheme 6) <2005CEC311>. 

H-Pyrrole-2-carboxylic acid, 5-nitro-, methyl ester 15N NMR, 4, 176 <76OMR(8)208> lH-Pyrrole-3-carboxylic acid, benzyl ester H NMR, 4, 166 <81UP30400>... 

Recently, the synthesis of 5-aryl-2-oxopyrrole derivative 210 as synthon for the highly substituted pyrrole 211 as starting compound for fused heterocycle 212 was published [56], Diethyl 6-bcnzyl-5-phenyl-6//-thieno[2,3-/ ]pyrrolc-2,4-dicarboxylatc 212 was prepared from ethyl l-benzyl-5-chloro-4-formyl-2-phcnyl-l //-pyrrolc-3-carboxylate 211 and ethyl 2-sulfanylacetate in refluxing ethanol (Scheme 41). 

Fig. 13 6-Methyl-2-[( )-(oxo-2-phenyl-l,3-oxazol-5(47/-ylidene)methyl]furo[2,3-fc] pyrrole-5-carboxylate 233b, 6-methoxymethyl-2-[( )-(oxo-2-phenyl-l,3-oxazol-5(4//-ylidene) methyl] furo[2,3-fc]pyrrole-5-carboxylate 233d [22] 3-benzyl-2-[( )-2-[5-(methoxycarbonyl)-6-methoxymethylfuro[2,3-fe]pyrrol-2-yl]vinyl -l,3-benzotiazolium bromide 234 [23]...

To a solution of 34.6 g of 2-(pyrrol-l-yl)benzyl alcohol in 300 ml of anhydrous tetrahydrofuran and 32 ml of tetramethylethylene diamine is added 183 ml of a 2.4 molar solution of n-butyl lithium in such a manner that the internal temperature of the reaction is maintained below 30°C. On completion of the addition, the reaction mixture is stirred at room temperature for 3 hours. The reaction mixture is then cooled to -70°C by means of a dry-ice/acetone bath, and 24 ml of ethyl pyruvate is added to the mixture over 1 minute. The reaction is then allowed to warm to room temperature and stirred overnight (18 hours). The reaction is then poured into an ice-water/ether mixture and the organic phase separated, dried over magnesium sulfate and the solvent evaporated under reduced pressure to yield ethyl-4-methyl-4H,6H-pyrrolo[l,2-a][4,l]benzoxazepine-4-carboxylate, MP 94°-96°C, which may be recrystallized from a mixture of ether-hexane (1 1). 

A -benzyl-3-methoxypyrrole-2-carboxylate, and searching for loss of the pyrrole. 

Abell et al. [288] reported the reaction of 5-formyl-lH-pyrrole-2-carboxylic amides bound to the polymeric support via their amide linkage (249) and dihydrocinna-moyl chloride. The acid chloride is believed to acylate the pyrrole nitrogen prior to an intramolecular Knoevenagel type condensation. The resulting bicycle (251) is deeply colored and was suggested by the authors to be used as a tag for combinatorial libraries. Upon treatment with NaOCHs, the bicycHc structure can be reverted to a 1-benzyl 3-pyrrolyl acrylic ester (Scheme 55). 

A practical synthesis of polysubstituted pyrrole-2-carboxylic esters is via the corresponding benzyl esters, the other functional groups are not affected under hydrogenolysis conditions. ... 

DBU is capable of inducing the elimination of /3-acetoxy nitroalkanes and deprotonation of benzyl isocyanoacetate. A tandem Michael-Henry reaction of the resulting species ensues, leading to 3,4-disubstituted pyrrole-2-carboxylic esters. 

Following formation of the S-Me derivative of ethyl 4-(1-benzyl-2-thia-oxopyrrolidin-3-yl)-5-(1,3-dioxobutyl)pyrrole-2-carboxylatewith methyl ir ide,the mixture was heated in a sealed Pyrex tube under nitrogen at SOX for 15 hours to produce ethyl 5-acetyl-6-benzyl-4-hydroxy-3,6,7,8-tetra-hydrobenzo-[1,2-b 4,3-b ]dipyrrole-2-carboxylate in 97% yield (ref.27)... 

Unlike the synthesis of phenols from non-aromatic sources that of thiophenol by similar methodology is virtually unknown. The synthesis shown of the diacetate of a tricyclic compound containing an o-substituted thiophenol system would appear to be applicable to the simpler central portion and to bicydic analogues. Ethyl 4-(1-benzyl-2-thioxo-pyrrolidin-3-yl)-5-(diazoacetyl)-pyrrole -2-carboxylate in dichloromethane was treated with boron trifluoride etherate in the same solvent and after 15 mins, the intermediate shown resulted which in a sealed tube (under vacuum) with acetic acid/acetic anhydride (3 1) at 132°C during 90mins. produced by a Pummerer rearrangement, ethyl... 

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