2- pyrroles. synthesis from

Dicarbonyl compounds pyridazine synthesis from, 3, 45 pyrrole synthesis from, 4, 329 reactions... 

Furan, 2,5-dialkoxy-2-( 1 -hydroxyalkyl)-2,5-dihydro-ring expansion, 1, 425 Furan, 2,5-dialkoxytetrahydro-pyrrole synthesis from, 4, 330 Furan, 2,4-dialkyl-synthesis, 4, 661, 685 Furan, 2,5-dialkyl-... 

PAAL - KNORR Pyrrole Synthesis Pyrrole synthesis from 1,4-butanedlone and amines. 

Pyrrole synthesis from at-dicarbonyl compounds.15 A new approach to N-benzyl-pyrroles is formulated for biacetyl as starting material (equation I). The method is also suitable for annelation of a pyrrole group to an a-methylene carbonyl compound. 

Ilac Knorr pyrrole synthesis from a-amino ketones and /3-dicarbonyl compounds 3.06.3.4.1... 

Ulace Hantzsch pyrrole synthesis from a-halocarbonyl compounds, /3-dicarbonyl 3.06.4.1... 

In attempts (76IZV690 80KGS1299 81MI4) to extend the pyrrole synthesis from ketoximes and acetylenes to aldoximes, the oximes of both aliphatic and aromatic aldehydes have been found to readily convert to the corresponding nitriles upon moderate heating (60-140°C) in KOH/DMSO. 

Several new examples of the Barton-Zard pyrrole synthesis from nitroalkenes and isocyanoacetate esters demonstrate the broad utility of this procedure. An excellent yield of ethyl 3-(9-anthryl)-4-ethylpyrrole-2-carboxylate was obtained starting with the nitroalkene from anthracene-9-carboxaldehyde and 1-nitropropane. <95TL8457> Bums et.al. reported an improved synthesis of benzyl isocyanoacetate which facilitates the synthesis of benzyl pyrrole-2-carboxylate esters by this method. <95SC379> 3-(l-Arylpyrrol-2-yl)pyrrole-2-carboxylates were prepared from l-aryl-2-(nitrovinyl)pyrroles. <95JHC 1703>... 

Scheme 8 Proposed mechanism for pyrrole synthesis from an amine, alkyne, and CO via zirconaaziridine...

In a similar context Amdtsen developed a new pyrrole synthesis from alkynes, acid chlorides either imines or isoquinolines, based on the reactivity of isocyanides (Scheme 35a) [197]. Although all atoms from the isocyanide are excluded from the final structure, its role in the reaction mechanism is crucial. The process takes place through the activation of the imine (isoquinoline) by the acid chloride to generate the reactive M-acyliminium salt, which is then attacked by the isocyanide to furnish a nitrilium ion. This cationic intermediate coordinates with the neighboring carbonyl group to form a miinchnone derivative, which undergoes a [3+2] cycloaddition followed by subsequent cycloelimination of the isocyanate unit, to afford the pentasubstituted pyrrole adducts 243 and 244 (Scheme 35a, b). 

F.H. Kohnke and co-workers prepared novel heterocyclophanes from cyclic poly-1,4-diketones, which were obtained by the oxidation of calix[6]furan and calix[4]furan. " One of the heterocyclophanes, calix[6]pyrrole, was prepared by the Paal-Knorr pyrrole synthesis from the corresponding dodecaketone. The substrate was heated with excess ammonium acetate in absolute ethanol. Interestingly, the analogous synthesis of calix[4]pyrrole under identical conditions failed, while calix[5]pyrrole is obtained only in 1% yield. 

Pyrroles, synthesis from keto oximes and aeetylene 80KGS1299. 

Pyrrole synthesis from 1,3-dicarbonyl compounds (or enamino Ketones) and a-amino acids via cyclization of enamino acid intermediates. 

A mixture of startg. nitroethylene, ethyl isocyanoacetate, and DBU in tetrahydro-furan stirred at room temp, for 15 h ethyl 3-hexyl-4-methylpyrrole-2-carboxylate. Y 78%. F.e.s. N. Ono, K. Maruyama, Bull. Chem. Soc. Japan 61, 4470-2 (1988) review of pyrrole synthesis from aliphatic compds. s. L.N. Sobenina et al., Russ. Chem. Rev. 58, 163-80 (1989). 

---