Pyrrole, 2-aryl-2,5-dihydro

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... 

Even in Ugi reactions of chiral 4,5-dihydro-3//-pyrrole derivatives with aryloxy substituents vicinal to the cWo-cyclic imino group, a low stereoselectivity was found with either chiral or achiral isocyanides and benzoic acid leading to substituted 2-aminoearbonyl-3-aryl-oxy-1 -benzoylpyrrolid ine derivatives82. 

Erba et al. (102) observed a novel formation of pyrrole imines 181 from the 1,3-dipolar cycloaddition of mtinchnones 179 and 5-amino-l-aryl-4,5-dihydro-4-methylene-1,2,3-triazoles 180 (Table 10.4). Treatment with benzaldehyde yielded 3-formylpyrroles (182). The reaction presumably involves loss of carbon dioxide, nitrogen, and morpholine from the initial cycloadduct. Unsymmetrical mtinchnones behave regioselectively and furnish products derived from bonding between C(2) of... 

Anwendung dieser Methode auf konjugierte Diene (z. B. 2,4-Hexadien, 1,3-Cyclooctadien) mit Anilinen als Amin-Komponenle fuhrt zur oxidativen Cycloaminierung, z.B. unter Bildung des betreffenden 1-AryI-2,5-dimethyl-2,5-dihydro-pyrrols bzw. 9-Aryl-9-aza-bicyclo[4.2.1]non-2-ensI. Das 1,3-Dienwird bei dieser Reaktion im UberschuB (2 equiv.) eingesetzt. 

Vilsmeier reaction, 4, 1051 Furo[3,2-6]pyrroles MO calculations, 6, 979 synthesis, 4, 1069 6, 1009 Furo[3,4-a]pyrrolo[2,1,5-cd]indolizine nomenclature, 1, 22 Furopyrylium salts, 4, 993-995 Furoquinolines biosynthesis, 4, 992 occurrence, 4, 988 pharmacology, 4, 992 reactions, 4, 988 synthesis, 4, 989 Furo[3,2-c]quinolines, 4, 991 Furo[3,4-fe]quinoxaline, 1,3-diphenyl-synthesis, 4, 993 Furoquinoxalines, 4, 992 Furo[2,3-6]quinoxalines synthesis, 4, 992 Furosemide toxicity, 1, 136 Furospinulosin UV spectra, 4, 587 Furospongin-I mass spectrometry, 4, 583 Furo[3,4-d][l,2,3]triazole, 2,6-dihydro-synthesis, 6, 996 Furo[3,4 -d][ 1,2,3]triazoles synthesis, 6, 996 Furoxan, 4-amino-3-aryl-tautomerism, 6, 404 Furoxan, 4-amino-3-methyl-synthesis, 4, 414 Furoxan, 4-aryl-3-methyl-rearrangement, 6, 408 Furoxan, 3-aryl-4-nitro-synthesis, 6, 414 Furoxan, 4-benzoyl-3-methyl-oxime... 

Supercritical carbon dioxide with a minute co-solvent addition is an effective medium for the 1,3-dipolar cycloaddition of azomethine ylides with DMAD to produce substituted pyrroles.67 The 1,3-dipolar cycloaddition of nitrile ylides [e.g. benzonitrile (4-nitrobenzylide) and 4-nitrobenzonitrile(benzylide)] with acrylamides provided a synthesis of 3,4-dihydro-2//-pyrroles with moderate to good yields.68 The Pt(II)-or Au(III)-catalysed 3 + 2-cycloaddition of the transition metal-containing azomethine ylide (63) with electron-rich alkenes provided a carbene complex (64), which yields tricyclic indoles (65) having a substituent at 3-position (Scheme 17).69 The 1,3-dipolar cycloadditions of azomethine ylides with aryl vinyl sulfones are catalysed by Cu(MeCN)4C104-Taniaphos with nearly complete exo- selectivity and enantioselec-tivities up to 85% ee.10 The 3 + 2-cycloaddition of benzol/>]thiophene 1,1-dioxide... 

The hypothesis about the formation of compounds like B was also proven by other authors [35, 36]. For example, the Padmavathi et al. [36] studied the reactions of heterocyclic analogues of chalcones 14 obtained from the appropriate diaroylacetones 13 and diazomethane (Scheme 2.5). It was shown that this treatment gives a solid which was identified as (4 -aryl-4/,5 -dihydro-l/Ff-pyrazol-3 -yl)-(4-aryl-l/f-pyrrol-3-yl)methanone 15. 

A.2.2 (4f-Aryl-4, 5 -dihydro-lfH-pyrazol-3f-yl)-(4-aryl-lH-pyrrol-3-yl)methanone... 

To a cooled solution of 2 (5 mmol) in dichloromethane (20 ml), an ethereal solution of diazomethane (40 ml, 0.4 M) and triethylamine (0.12 g) was added (Scheme A.9). The reaction mixture was kept at —20 to — 15 °C for 40-48 h. The solvent was removed under reduced pressure. The resulting solid, (4 -aryl-4, 5 -dihydro-l i/-pyrazol-3 -yl)-(4-aryl-l//-pyrrol-3-yl)methanone 3, was purified by recrystallization from methanol. 

A wide variety of substituents are tolerated. The group R can be alkyl, halogen, alkoxy, -amido, azi-domethyl, ester, aryl, aryloxy and aryloyl, and at least one ortho substituent is permissible with no loss in yield. TTie aromatic ring can also be 2-naphthyl, 9,10-dihydro-2-phenanthryl, 3-pyridyl, thiophen-2-yl or pyrrol-3-yl. The group R can be hydrogen, yl, acyl or acetic acid. Beyond Ae antiinflammatory targets, successful reaction substrates include the methyl ketones of a binaphthyl crown ether, a morphinane and a polyaromatic hydrocarbon. The preparation of ibuprofen methyl ester (38) is shown in equation (37) as a typical example. ... 

The reactions of alkenyl carbene complexes with isonitriles can produce a variety of products whose distribution is sensitive to the nature of the isonitrile. Reacting 3 equiv. of aryl isonitrile with the alkenyl complex (383) produces the dihydro- y-carbolinone (385). 74 The ketenimine in (384) is liberated with a second equivalent of the isonitrile, and the the third equivalent undergoes a formal [4 -i- 2] cycloaddition with the free ketenimine. With sterically encumbered isonitriles, the ketenimine is more rapidly liberated from the metal by a second isonitrile and 2 equiv. are required to drive the reaction to completion. Free ketenimines that are generated in this manner can be trapped via their [4 + 2] cycloadditions with maleic anhydride. 7 Primary and secondary alkyl isonitriles will react with alkenyl carbene complexes to give cycloadducts that can be converted to pyrroles or products that contain five-member ring carbo-cycles. 7 ... 

Examples of related photochemical (hetero)arylations are the pentafluoralkyla-tion of pyrroles and indoles by irradiation in the presence of pentafluoroiodo-benzene or of pentafluorophenyl perfluoroalkanesulfonates [97], and presumably also the acetone-sensitized photocoupling of 5-bromo-l,3-dimethyluracil (47) with indoles. The latter reactions apparently follow an ET path, rather than the homo-lytic debromination which occurs on direct irradiation (Scheme 32) [98]. A different arylation leads to 2,5-dihydro-2-(4 cyanophenyl)-5-methoxyfuran on irradiation with 1,4-dicyanobenzene in methanol [99]. 

The methods described for arylation of dihydrofurans (see above) have also been applied to 2,3-dihydropyrroles such as 63 [55], with similar patterns of re-gio- and enantioselectivity being observed. Thus little or no ee was obtained when using aryl iodides, but aryl triflates gave mixtures of 2-aryl-2,3-dihydro-pyrroles 64 and 2-aryl-2,5-dihydropyrroles 65, with the former predominating and the kinetic resolution process again being in effect, as evidenced by another inverse relationship between the ee of 64 and the 64 65 ratio (Scheme 16). The reaction was also successfully extended to vinyl triflates, which gave even better ee s than obtained for the dihydrofurans [50]. 

The use of saturated 1,4-diketones can suffer from the disadvantage that they can react with hydrazine in two ways, giving mixtnres of the desired dihydro-pyridazine and an iV-amino-pyrrole this complication does not arise when nnsatnrated 1,4-diketones are employed. There is also no structural ambiguity when aryl-hydrazines are reacted with pent-4-ynoic acid catalysed by zinc chloride, producing 2-aryl-3,4-dihydro-... 

Aryl-l,2,4-triazin-5(2//)ones react with indoles, pyrroles, pyrazoles and thiazoles in boiling butanol, and some other solvents, to give addition products e.g. 62. Oxidation results in aromatization <97JHC1013>. They also react with phenols and dialkylanilines to give 6-aryi-l,6-dihydro-l,2,4-triazin-5(2//)ones <97JHC573>. 

Scheme 25 Ru-catalyzed C2-arylation/alkylation of pyrrolidines and piperidines substituted at nitrogen with a 2-pyridinyl or 3,4-dihydro-2H-pyrrol-5-yl directing group and removal protocols (2006JA14220, 2013JOC9803).

The intramolecular acylation has proven to be quite general, regardless of substituents attached on the pyrrole ring. As demonstrated in the synthesis of 15, the presence of a protected amine at C(2) is tolerated. Similarly, a large number of 5-aryl-1,2-dihydro-1-pyrrolizinones (17), compounds with anti-inflammatory and analgesic properties, have been synthesized using this method. ... 

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