A Novel Route to Certain 2-Pyrrolecarboxylic Esters and Nitriles<sup>1,2</sup>

Kleinspehn, George G.

doi:10.1021/ja01611a043

Cited by 111 publications

(37 citation statements)

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“…Since a-aminoketones are rather reactive and difficult to handle, the practical procedures often involve generation thereof in situ from a suitable synthetic equivalent, as illustrated by the classical example below (Scheme 4. 19), in which addition of one equivalent of sodium nitrite to two equivalents of ethyl acetoacetate (55) generates an oxime, which, upon reduction with zinc dust [110,111] It has also been demonstrated that this reaction may follow a different path if a b-diketone is used as one of the reactants, as treatment of diethyl oximinomalonate (57) with 2,4-pentanedione (58) under reductive conditions will afford ethyl 3,5-dimethylpyrrole-2-carboxylate (59) [113]. Since this process involves the intermediacy of diethyl aminomalonate (60), the reductive conditions can be avoided by using this very reagent.…”

Section: 42mentioning

confidence: 99%

Five‐Membered Heterocycles: Pyrrole and Related Systems

Bergman

Janosik

2011

Modern Heterocyclic Chemistry

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Section: 42mentioning

confidence: 99%

Five‐Membered Heterocycles: Pyrrole and Related Systems

Bergman

Janosik

2011

Modern Heterocyclic Chemistry

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“…The first step towards the strapped porphyrin was to link the dicarboxylic acids to two P-unsubstituted pyrroles 18 (20,21) via Friedel-Crafts alkylation reactions. The pyrroles were acylated with the corresponding bisacid chloride 17 in a mixture of methylene chloride and nitromethane using anhydrous stannic chloride as the catalyst.…”

Section: R : ( C H~)~c O O H X : Iv02mentioning

confidence: 99%

“…This included the removal of the ethyl ester, thermal decarboxylation of the resulting diacid, and forinylation of the unsubstituted a-position by the Vilsmeier reaction (20)(21)(22). Since the direct saponification of the ethyl ester 20 led to extensive decomposition, the acids could only be obtained via a transbenzylation-debenzylation route.…”

Section: R : ( C H~)~c O O H X : Iv02mentioning

confidence: 99%

Synthesis and characterization of derivatized capped porphyrins

Tang¹,

Wijesekera²,

Dolphin³

1992

Can. J. Chem.

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This paper is dedicated to Professor Zder~ek (Denny) Valenta on the occasiorz of his 65th birthdayHANG TANG, TILAK P. WIJESEKERA, and DAVID DOLPHIN. Can. J. Chem. 7 0 , 1366 (1992)The syntheses of porphyrins carrying either a fully hydrophobic cavity with a benzene moiety (32a,b) or a polar cavity with an amidobenzene (32c-d) are described. Terephthaldehyde ( 1 ) was converted to benzene-bisalkanoic acids ( 8 , 10) and nitrobenzene-bisalkanoic acids (13 and 16) by using standard methods. The corresponding diacid chlorides 17a-d were used to acylate two equivalents of a P-unsubstituted pyrrole, and the ketonic groups were reduced by diborane. Following the transformation of the nitro function to the acetamide, appropriate modifications of the ethyl ester functions afforded the key bisformylpyrroles 2%-d. The cyanoacrylate-protected formyl pyrrole derivatives were monochlorinated at the a-methyl groups and condensed with two equivalents of an a-unsubstitutued pyrrole to give the dipyrromethane dimers. Strong aqueous alkali caused saponification of the two ester groups and deprotection of the formy1 functions to produce the dipyrromethane dimer 30, which, after thermal decarboxylation, was cyclized intramolecularly in acidic medium to give the porphyrins 32 (n = 4 or 5, X = H or NHCOCH,).HANG TANG, TILAK P. WIJESEKERA et DAVID DOLPHIN. Can. J. Chem. 7 0 , 1366 (1992).On dCcrit la synthkse de porphyrines portant soit une cavite complktement hydrophobe avec une portion benzCnique (32a,b) soit une cavitC polaire avec un amidobenzkne (32c-d). Utilisant des mCthodes courantes, on a transform6 le tCrCphtaldChyde ( 1 ) en acides benzkne-bisalcano'iques ( 8 , 10) et en acides nitrobenzene-bisalcanoiques (13 et 16). On a utilisC les chlorures d'acides correspondants (17a-d) pour acyler deux Cquivalents d'un pyrrole non substituk en position p, puis on a reduit les groupes cCtoniques avec du diborane. Aprks avdir transform6 lei fonctions nitro en acktamide, des modifications appropriCes des fonctions esters Cthyliques ont fourni les bis-formyl pyrroles 25a-cl clCs. On a effectuC une monochloration des dCrivCs du forrnyl pyrrole protCgCs par le cyanoacrylate sur les groupes mCthyles en a et on a condens6 les produits avec deux equivalents d'un pyrrole non substitue en a afin d'obtenir des dimbres dipyrromkthanes. Sous l'influence de solutions alcalines aqueuses concentrees, il se produit une saponification des deux groupes esters et une deprotection des fonctions formyles pour conduire au dimbre dipyrromethane 30 qui, aprks dtcarboxylation

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“…: C 68,33, H 6,15, N 7,77; tr. : C 6 8 3 , H 5,93, N 7,98. De la mCme manikre est obtenu le dipyrrylmethane 6i A partir du 1360 cm-'; rmn 'H (CDCI,): 1,7 (s, 6H), 2,2 (s, 6H), 5,2 (s,4H),6,2 (s,IH),8 (m,13H),8,8 (s large,2H). Anal.…”

Section: Synthkse De Dipyrryltnethanesunclassified