Pyrrole, 2-ethyl

K.21) 1//-Pyrrole, 2-ethyl-5-methyl-, 2-ethyl-5-methy/pyrrole [765-94-6]... 

Since, the original presentation of this paper, the pheromone of the Mediterranean fruit fly has been identified (23). The compounds, 3,4-dihydro-2H-pyrrole, ethyl-E-3-octenoate, E,E,-0(-farnesene, and geranyl acetate, bear no obvious resemblance to the active components of trimedlure. The origin of the biological activity of the synthetic, therefore, remains enigmatic. 

A similar synthesis to give octaacetic acid porphyrin is much less productive (Chiusoli et al., 1989). Highly substituted porphyrins with eight P-pyrrolic ethyl groups and four phenyl groups in the meso positions have been obtained similarly. The latter, highly overcrowded porphyrins (see chlorophyll synthesis) are totally stable (Evans et al., 1977). 

Method Seven, Signaigo and Adkins (725). Pyrrole + ethyl magnesium bromide + ethyl chlorocarbonate -> 1,2-dicarbethoxypyrrole -> 1,2-di-carbetboxypyrrolidine proline. Adkins and coworkers (45, 653, 724) have shown that the pyrrole nucleus requires more drastic conditions for reduction than the benzenoid nucleus, that the N-carbethoi substituent decreases resonance so that the pyrrole ring may be hydrogenated under mild conditions and that this substituent is more effective in the 1-than the 2-position. The synthesis of proline by the reduction of 2-carboxypyrrole (312, 297, 647) or of 2-carboxy-a-pyrrolidone (294, 539, 540) has not been successful for these reasons. 

Hantzsch synthesis The formation of pyridine derivatives by the condensation of ethyl acetoacetate with ammonia and an aldehyde. Also applied to similar syntheses of pyrroles. 

The preparation of 2 4-dimethyl-3 5-dicarbethoxypyrrole (II) is an example of the Knorr synthesis of pyrrole derivatives, involving the reaction of an -aminoketone (or a derivative thereof) with a reactive methylene ketone (or a derivative thereof). The stages In the present synthesis from ethyl acetoacetate (I) may be represented as follows ... 

Ethyl-4-methyl-l-(phenylsulfonyl)indole 4-Ethyl-7-methyl-l-phenylsulfonyl-l,5-dihydropyrano-[3,4-b]pyrrol-5-one phenyl vinyl sulfoxide 60 [3]... 

Methoxycarbonyl)-7-methyl-l-(phenylsulfonyl)- 5-trimethylsilylindole 7-Methyl-l-phenylsulfonyi-l,5-dihydropyrano[3,4-b]pyrrol-5-one ethyl 3-trimethyIsilyIpropynoate 53 [1]... 

Pyrrole oxidizes in air to red or black pigments of uncertain composition. More usehil is the preparation of 2-oxo-A -pyrrolines, which is best carried out by oxidation of the appropriate pyrrole with in pyridine (37), eg, 3,5-dimethyl-ethyl-3-pyrrolin-2-one [4030-24-4] from... 

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). 

The high reactivity of pyrroles to electrophiles is similar to that of arylamines and is a reflection of the mesomeric release of electrons from nitrogen to ring carbons. Reactions with electrophilic reagents may result in addition rather than substitution. Thus furan reacts with acetyl nitrate to give a 2,5-adduct (33) and in a similar fashion an adduct (34) is obtained from the reaction of ethyl vinyl ether with hydrogen bromide. 

A -Amino- and A-substituted amino-pyrroles readily undergo Diels-Alder additions and add to activated alkynes at room temperature. The resulting azanorbornadienes extrude A-aminonitrenes and this forms the basis of an unusual synthesis of benzene derivatives (81S753,81TL3347). It has been found that ethyl/3-phenylsulfonylpropiolate (135) is a superior dienophile to DMAD (Scheme 50). 

Remarkably few examples of this type of ring construction are available. The cobalt carbonyl hydride catalyzed hydroformylation of A/,A/ -diallylcarbamates has provided 3-pyrrolidinones (Scheme 61a) (81JOC4433). The pyrrole synthesis shown in Scheme 61b depends on Michael addition of ethyl a-lithioisocyanoacetate to ethyl a-isocyanocrotonate (77LA1174). 

H-Pyrrole-2-carboxylic acid, 4-ethyl-3-methyl-5-thienoyl-, ethyl ester X-ray, 4, 160 (78AX(B)2929> lH-Pyrrole-2-carboxylic acid, 5-methyl-, ester X-ray, 4, 160 (76T2057)... 

H-Pyrrole-3-carboxylic acid, ethyl ester C NMR, 4, 172 (74JCS(P2)1004>... 

UV, 6, 1032 (74JA4268) 47/-Thieno[3,4-c]pyrrol-5-ium-4-ide, 5-methyl-UV, 6, 1032 (74JA4268) 47/-Thieno[3,4-c]pyiTol-5-ium-4-ide, 5-phenyl-UV, 6, 1032 (74JA1817) l-(2-Thienyl)ethyl acetate kinetic data, 4, 952 (77AHC(21)119>... 

Pyrrole, 3,4-dialkyl-2-ethyl-5-methyl-benzoylation, 4, 220 Pyrrole, 1,2-diamino-reactions, 4, 300 Pyrrole, 2,5-diamino-tautomerism, 4, 200, 299 Pyrrole, 2,4-diaryl-nitration, 4, 210 Pyrrole, 2,5-diaryl-synthesis, 4, 343 Pyrrole, 3,4-diaryl-synthesis, 4, 343 Pyrrole, di-t-butyl-protonation, 4, 47 Pyrrole, 2,5-dichloro-synthesis, 4, 368... 

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... 

Pyrrole-2-carboxylic acid, 4,5-dimethyl-ethyl ester formylation, 4, 217 Pyrrole-2-carboxylic acid, 3-hydroxy-... 

Pyrrole-3-carboxylic acid, l-benzoyl-5-bromo-2,4-dimethyl-ethyl ester chlorination, 4, 271... 

Thieno[2,3-d ]pyrimidin-4(3 H) -one, 3-methyl-synthesis, 4, 1017 Thieno[2,3-d ]pyrimidin-4-ones synthesis, 4, 1017, 1018, 1022 Thieno[2,3-6]pyrrole, 5-aryl-synthesis, 6, 1009 Thieno[2,3-6]pyrrole, N-benzyl- H NMR, 4, 1042 UV spectra, 4, 1044 Thieno[2,3-c]pyrrole, N-ethyl-UV spectra, 4, 1044 Thieno[3,2-6]pyrrole, 5-aryl-synthesis, 6, 1009 Thieno[3,2-6]pyrrole, N-benzyl- H NMR, 4, 1041, 1042 lithiation, 4, 1051 UV spectra, 4, 1044 Thieno[3,2-6]pyrrole, 2,3-dihydro-desulfurization, 6, 984 oxidation, 6, 981... 

The Teoc group is introduced onto pyrroles, or indoles with 4-nitrophenyl 2-(tri-methylsilyl)ethyl carbonate and NaH in 61-64% yield. The Teoc group can be removed with Bu4N F in CH3CN. ... 

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