864. The synthesis of tri- and tetra-alkylpyrroles

Johnson, A. W.; Markham, E.; Price, R.; Shaw, K. B.

doi:10.1039/jr9580004254

Cited by 47 publications

(23 citation statements)

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“…The synthetic route to asymmetric 3,8‐dichloro‐BODIPY 1 a is outlined in Scheme . The conversion of the α‐methyl group of readily available pyrrole 2 a 21 to a carboxylic acid produced 2 b ,22 which was acylated with thionyl chloride followed by reaction with dimethylamine gas22b affording 5‐( N , N ‐dimethylamido)pyrrole 2 c in 85 % yield. The asymmetric dipyrroketone 3 was prepared by reaction of pyrrole 2 c with phosphoryl chloride, followed by addition of commercially available 3‐ethyl‐2,4‐dimethylpyrrole and subsequent hydrolysis using aqueous sodium acetate23 in 86 % overall yield.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of 3,8‐Dichloro‐6‐ethyl‐1,2,5,7‐tetramethyl–BODIPY from an Asymmetric Dipyrroketone and Reactivity Studies at the 3,5,8‐Positions

Zhao

Vicente

Fronczek

et al. 2015

Chemistry A European J

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The asymmetric BODIPY 1a (BODIPY=4,4-difluoro-4-bora-3a,4a-diaza-s-indacene), containing two chloro substituents at the 3,8-positions and a reactive 5-methyl group, was synthesized from the asymmetric dipyrroketone 3, which was readily obtained from available pyrrole 2a. The reactivity of 3,8-dichloro-6-ethyl-1,2,5,7-tetramethyl-BODIPY 1a was investigated by using four types of reactions. This versatile BODIPY undergoes regioselective Pd0-catalyzed Stille coupling reactions and/or regioselective nucleophilic addition/elimination reactions, first at the 8-chloro and then at the 3-chloro group, using a variety of organostannanes and N-, O-, and S-centered nucleophiles. On the other hand, the more reactive 5-methyl group undergoes regioselective Knoevenagel condensation with an aryl aldehyde to produce a monostyryl-BODIPY, and oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) gives the corresponding 5-formyl-BODIPY. Investigation of the reactivity of asymmetric BODIPY 1a led to the preparation of a variety of functionalized BODIPYs with λmax of absorption and emission in the ranges 487–587 and 521–617 nm, respectively. The longest absorbing/emitting compound was the monostyryl-BODIPY 16, and the largest Stokes shift (49 nm) and fluorescence quantum yield (0.94) were measured for 5-thienyl-8-phenoxy-BODIPY 15. The structural properties (including 16 X-ray structures) of the new series of BODIPYs were investigated.

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Section: Resultsmentioning

confidence: 99%

“…Benzyl‐3,4,5‐trimethylpyrrole‐2‐carboxylate ( 2 a )21 (4.34 g, 17.84 mmol) was dissolved in carbon tetrachloride (270 mL). Sulfuryl chloride (7.69 g, 57 mmol) was added dropwise and the resulting solution was stirred overnight at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of 3,8‐Dichloro‐6‐ethyl‐1,2,5,7‐tetramethyl–BODIPY from an Asymmetric Dipyrroketone and Reactivity Studies at the 3,5,8‐Positions

Zhao

Vicente

Fronczek

et al. 2015

Chemistry A European J

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“…Crystals were handled as described by Hope (1994). The compounds were prepared as described previously (Ku È ster, 1922;Fischer & Stern, 1940;Hayes et al, 1958;Johnson et al, 1958;Kenner et al, 1977) and crystallized from CH 2 Cl 2 /n-hexane.…”

Section: Methodsmentioning

confidence: 99%

Hydrogen-bonding patterns in six derivatives of 2,4-dimethylpyrrole

Senge

Smith

2005

Acta Crystallogr C

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The crystal and molecular structures of 4-ethyl-3,5-dimethylpyrrole-2-carbaldehyde, C10H15NO, (I), benzyl 3,5-dimethylpyrrole-2-carboxylate, C14H15NO2, (II), benzyl 4-acetyl-3,5-dimethylpyrrole-2-carboxylate, C16H17NO3, (III), dimethyl 3,5-dimethylpyrrole-2,4-dicarboxylate, C10H13NO4, (IV), 4-ethyl-3,5-dimethyl-2-(p-tosylacetyl)pyrrole, C17H21NO3S, (V), and ethyl 4-(2-ethoxycarbonyl-2-hydroxyacryloyl)-3,5-dimethylpyrrole-2-carboxylate, C15H19NO6, (VI), were determined at 130 K. Compounds (I), (II), (IV), (V) and (VI) form hydrogen-bonded dimers [N-H...O=C=1.97 (2)-2.03 (3) A]. Four dimers, viz. (I) and (IV)-(VI), have inversion symmetry, while the dimer of (II) has twofold symmetry. Only (III) forms polymeric chains involving hydrogen bonds between the pyrrole H atom and the acetyl carbonyl group [H...O=1.97 (2) A] and is further stabilized by CH3...O interactions (C-H...O=2.28-2.49 A). Compound (VI) was found to occur as the enol ether in the crystal.

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“…Substituted pyrroles were synthesized by standard methods (9) or recent variations on these methods (10,11). Pyrrole was a commercial sample (Fisher) repeatedly redistilled to give a fraction of lo boiling range; other liquid compounds were distilled similarly.…”

Section: Methodsmentioning

confidence: 99%

Physical Properties of Alkyl Pyrroles and Their Salts

Abraham¹,

Bullock²,

Mitra³

1959

Can. J. Chem.

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The structures of the ions formed by several alkyl pyrroles in hydrochloric acid are deduced from proton resonance spectra. Basicity values for three alkyl pyrroles are determined from ultraviolet spectra of their salts in buffer solutions. An attempt is made to estimate the basicity of other pyrroles from the variation of the—OD stretching frequency of methanol-d in solution in the pyrroles. Variations of the free and bonded NH frequencies of alkyl pyrroles are shown to be a simple function of the positions and number of the substituents.

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864. The synthesis of tri- and tetra-alkylpyrroles

Cited by 47 publications

References 0 publications

Synthesis of 3,8‐Dichloro‐6‐ethyl‐1,2,5,7‐tetramethyl–BODIPY from an Asymmetric Dipyrroketone and Reactivity Studies at the 3,5,8‐Positions

Synthesis of 3,8‐Dichloro‐6‐ethyl‐1,2,5,7‐tetramethyl–BODIPY from an Asymmetric Dipyrroketone and Reactivity Studies at the 3,5,8‐Positions

Hydrogen-bonding patterns in six derivatives of 2,4-dimethylpyrrole

Physical Properties of Alkyl Pyrroles and Their Salts

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