Pyrrole-based derivatives

On distillation with zinc dust the alkaloid gives an easily hydrogenated pyrrole base, and on dehydrogenation by platinised asbestos at 260-290 it yields (1) an amorphous dehydro-base, which forms an oxime and a methiodide, C17H23O4N. Mel, decomp. 227-8 , and contains a lactone and a methoxyl group, (2) a neutral pyrrole derivative, and (3) an acid giving a dark green colour with ferric chloride (1939). 

The synthesis of a pyrrole segment common to netropsin and distamycin is shown in Scheme 2ji°l Friedel-Crafts acylation of 1-methylpyrrole (1) followed by nitration at C4 provides 3 in 54% yield. After a haloform reaction, hydrogenolysis, N-protection with B0C2O, and saponification, the pyrrolecarboxylic derivative acid 7 was obtained in 30% overall yield from 3. This monomer is readily chain-extended to the pyrrole-imidazole derivative 9 (Scheme 3)J10 Furthermore, solid-phase synthesis with this and related pyrrole-containing building blocks leads to polyamides that have recently been used in the recognition of a 16 base-pair sequence in the minor groove of DNA.1" ... 

Reactions involving primary amines have been successfully carried out via Schiff s bases derived from a number of aldehydes. Thus, the reaction of pyrrole with the protonated enamine (1), which results in the formation of the pyrrole trimer (2 equation 1), constitutes a good example of a Mannich reaction involving an aldehyde other than formaldehyde. ... 

Pyrrole-based anthranilic acid derivatives have been prepared utilizing a four step sequence starting from arylacetonitriles 4 <04T2267>. Condensation of the latter with ethyl formate followed by treatment with diethylaminomalonate hydrochloride (DEAM-HCl) led to enamine 6. Cyclization and transesterification then gave 3-aminopyrrole-2-carboxylate 7. The acid-mediated cyclocondensation of methylaminoacetaldehyde dimethyl acetal with malonitrile provided a novel synthesis of 2-amino-3-cyanopyrroles, useful building blocks for the preparation ofpyrrolo[2,3- f]pyrimidines <04OL2857>. 

Schiff base derived from pyrrole-2-carboxaldehyde and 3-amino-... 

In addition to the FBI complexes, several additional classes of ethylene polymerization catalysts based upon tridentate ligand complexes of iron have been developed. These include the furan, 5, and pyrrole, 6, derivatives. The oxidation state of the... 

Cyclic (pyrrole) acetals derived from 2,2-dimethylpropanediol have recently been used successfully in protection of the aldehyde group and in some base catalyzed reactions, and the parent acetal (13) and some derivatives have now been prepared. A useful new formylation procedure involves treatment of appropriate pyrroles with triethylorthoformate and trifluoroacetic acid. ... 

FIGURE 4.7 (a) Anion-binding mode of pyrrole-based anion receptor 14a (b) anion receptor derivatives 14-17. 

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