Pyrroles and Related Compounds

Near-degenerate states lead to oppositely signed terms that occur at nearly the same energy leading to a overall spectral feature that looks like an A term and is called a pseudo-A term (11). In many cases it may be that a quick SOS calculation may be sufficient to describe a pseudo-A term. We have had some success in describing the MCD spectra of furan, pyrrole, and related compounds through this approach (98). 

PYRROLE AND RELATED COMPOUNDS. [CAST 09-97-7]. Pyrrole (monoazole, C4H5N or C4H4NH), contains a ring of 1 nitrogen and 4 carbons, with 1 hydrogen attached to nitrogen and to each carbon ... 

Pyrroles and related compounds were reviewed by Maga 215 37 pyrroles from about 20 model systems have been tabulated by Vemin and Parkanyi.216... 

The formation of borylated heterocyclic compounds has attracted much interest with regard to their use as starting materials for cross-coupling reactions, the possible formation of interesting macrocyclic species, and their applications in optoelectronic materials. Several synthetic routes are available for the borylation of the five-membered heterocycles thiophene, furan, pyrrole, and related compounds (101-103 ... 

Cox, M. T., Howarth, T. T., Jackson, A. H., Kenner, G. W. (1974a). Pyrroles and related compounds. Part XXVUI. (3-Keto-esters in the porphyrin series, J. Chem. Soc., Perkin Trans.l, p. 512. 

Uhr H, Lui N, Erdelen C, Tuibeig A (1995) Preparation of 2-aryl-3,4,5-ttis(ttifluoromethyl) pyrroles and related compounds as pesticides. Patent DE 4325132... 

M. Shiotani, Y. Nagata, M. Tasaki, J. Sohma, and T. Shida. 1983. Electron spin resonance studies on radical cations of five-membered heteroaromatics. Furan, thiophene, pyrrole, and related compounds. / Phys Chem 87(7) 1170-1174. 

Synthesis of pyrrole, pyrazole, and thiazole derivatives using conjugated azoal-kenes and related compounds 97SL1128. 

This class of tricyclic compound is dominated by the 377-pyrrolizines (systematically named 3//-pyrrolo[l,2- ]-pyrroles) and related systems, which are fused to another six-membered heterocyclic ring (Figure 1). 

Bossio R, Marcaccini S, Pepino R (1994) Studies on isocyanides and related compounds a novel synthesis of pyrroles via Ugi reaction. Synthesis 8 765-766... 

The action of phosphorus halides on pyrrolinones and related compounds offers an alternative route to chloropyrroles. Yields of around 60% of 2,5-dichloropyrroles were obtained in this way from N-substituted succinimides (82ZC126). Vilsmeier reaction of N-alkylsuccinimidals formed chlorinated pyrrole aldehydes in modest yields (90CJC791), and there are other examples [66YZ158 81H(15)547]. A useful synthesis of chloropyrrole-2-carboxylates employed the action of phosphorus pentachloride on pyrrolidin-2-one-5-carboxylates (40) (87CB45) (Scheme 15), and in a Pummerer-type reaction pyrrol-3-yl sulfoxides were transformed by thionyl chloride into chloropyrroles. Yields were increased to >80% by the use of oxalyl chloride (88JOC2634) (Scheme 15). 

O., Koehler, R., Kluge, A. F., etal. Synthesis and antiinflammatory and analgesic activity of 5-aroyl-1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1 -carboxylic acids and related compounds, J. Med. Chem. 1985, 28, 1037-1049. 

Bis(2-pyrrolyl) sulfides, prepared from the reaction of the pyrrole with sulfur dichloride, are useful precursors in the synthesis of corroles and related compounds, as it is possible to cause the extrusion of the sulfur atom with the consequent formation of a bipyrrolic unit within the macrocycle <72JCS(P1)1124). 

In addition, there are [5 -> 3 + 2] fragmentations leading to acyclic products that result from the original fragments by rearrangement. Examples are 5-phenyl-l,2,3,4-thiatriazole (50) and related compounds with three ring heteroatoms and an exocyclic double bond (51),THF (52), y-butyrolactone (53), y-thiobutyrolactone (54), pyrroles (8,61), pyrrolidine (55), furans (56, 58), pyrazole (62), and isoxazoles (11, 63,64). Most of these molecules are thermally rather stable and their decomposition requires drastic conditions. 

---