Pyrrole, 1-phenyl-, hydrogenation

Substitution of pyrrole hydrogens by Br and/or of phenyl hydrogens by Cl and/or F gave an increased activity [117,118]. 

Intramolecular hydrogen abstraction leading to the aziridine 344 has been proposed to account for the unexpected conversion of the /f-amino vinyl phenyl ketones 345 into the pyrroles 346.286... 

Stang etal. (94JA93) have developed another alkynyliodonium salt mediated approach for the synthesis of y-lactams including bicyclic systems containing the pyrrole moiety. This method is based on the formation of 2-cyclopentenones 114 via intramolecular 1,5-carbon-hydrogen insertion reactions of [/3-(p-toluenesulfonyl)alkylidene]carbenes 113 derived from Michael addition of sodium p-toluenesulfinate to /3-ketoethynyl(phenyl) iodonium triflates 112 (Scheme 32). Replacing 112 by j8-amidoethynyl (phenyl)iodonium triflates 115-119 provides various y-lactams as outlined in Eqs. (26)-(30). 

The reaction of isopropyl phenyl ketoxime with acetylene in the KOH/ DMSO system was the first to show that ketoximes having only an aliphatic hydrogen atom in the a-position with respect to the oxime function can serve as the starting material for the synthesis of inaccessible 3//-pyrroles. 

The reaction of ethyl 2-phenyl-4//-furo[3,2-/>]pyrrole-5-carboxylate (94) with 2-nitrobenzyl-oromide afforded ethyl 4-(2-nitrobenzyl)-2-phenylfuro[3,2-6]pyrrole-5-carboxylate (269) under conditions of phase transfer catalysis by utilization of sodium carbonate and tetrabutylammonium bromide. This product (269) was hydrogenated using palladium-on-charcoal catalyst to give the amine (270), which cyclized in the presence of 2-hydroxypyridine to give 2-phenylfuro[2, 3 4,5]pyrrolo[2,l-c]benzo[l,4]diazepin-l 1-one (271) <92CCC1487>. 

A mixture of l,2-dimethyl-3-acetyl-4-isopropyl-5-phenyl pyrrole (12.75 g, 0.05 mol) and diethyl isopropylidene succinate (10.7 g, 0.05 mol) in dry toluene (70 ml) was added to a stirred solution of sodium hydride (80% dispersion in oil, 3.8 g, 0.125 mol) suspended in dry toluene (10 ml) under nitrogen atmosphere. A few drops of absolute ethanol were added to initiate the exothermic reaction. The reaction mixture was stirred for about 40 h at ambient temperature until no hydrogen was formed, and finally the reaction mixture was poured into crashed ice-water (100 ml). The organic layer was separated and extracted with saturated sodium carbonate solution (2 x 50 ml). The combined aqueous layer was extracted with toluene (50 ml), and then the aqueous phase was acidified slowly with 5 M hydrochloric acid and washed with toluene (3 x 100 ml). The toluene solution was dried with MgSO 4 and the solvent was removed the half-ester was obtained as a gum. 

As with the multi-species components, it is not necessary for hydrogen bonding to be used in order to form dimeric capsules. This is highlighted by the recent synthesis of a molecule which assembles into dimers that are held together by n-interactions [137]. The meso-hexaphenyl calix[6]pyrrole 59 assembles into a dimeric capsule via the interactions between six phenyl groups arranged in a central belt around the capsule. The capsule is capable of holding two molecules of chloroform simultaneously, as seen in the solid state structure (Fig. 51). Similar phenyl interactions have been observed in ap-phenylcalix[5]arene which has been shown to dimerise and include C60 within its cavity (Fig. 52) [138]. 

Pyrrole and N-substituted pyrroles are formed by a reaction analogous to the conversion of sugars to furan aldehydes. Ammonium and substituted ammonium salts of mucic acid, H02C(CH0H)4C0jH, are cyclized and de-carboxylated by pyrolysis. The yields of pyrrole and its N-phenyl and N-methyl derivatives are about 40%. Tetrahydropyrroles (pyrrolidines) are formed from various 4-substituted amines by elimination of water, ammonia, or hydrogen halide. ... 

Figure 26. A force-field (CHARMm) optimized structure of porphyrin 20 with the peptide gly-gly-phe. Hydrogens are omitted for clarity except those of peptide NH3. The phenyl group of phe is not far from vdW contacts to the pyrrole (dav = 3.95 A) the -NH3 protons have distances from 1.90 to 2.05 A to the crown ether oxygen the carboxylate group comes close to neighboring pyridyl protons with dav = 3.0 A. ...

Prodncts of 2- and 4-snbstitntion of hydrogen are obtained by reaction of the sodium salt of imidazole with the phenyl pyrimidin-5-yl carbinol mesylate, with none of the product of direct substitution. Similar resnlts are obtained with the sodium salts of pyrrole and indole, but other nucleophiles, such as amines, give complex product mixtures. " ... 

In the pyrolysis of proteins, the dominant mechanism is the splitting-off of the amino acids rather than break-up of the backbone into smaller fragments which are characteristic of the original amino acids.Usually highly characteristic signals are found for the aromatic and sulphur containing amino acids, e.g., hydrogen sulphide from cystine and in combination with methionine pyrrole pyrrolidine and methylpyrrole for proline, phenyl, and cresol from tyrosine, toluene, styrene and phenylacetonitrile for phenylalanine indole, and methylindol from tryptophan. 

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