Pyrrole Chemistry. XV. The Chemistry of Some 3,4-Disubstituted Pyrroles

1973 ◽  
Vol 51 (7) ◽  
pp. 1089-1098 ◽  
Author(s):  
John Kington Groves ◽  
Niven Eddy Cundasawmy ◽  
Hugh John Anderson
Keyword(s):  
Raney Nickel ◽  
Aluminum Chloride ◽  
Alder Reaction ◽  
Subsequent Treatment ◽  
Diels Alder ◽  
Partial Hydrolysis ◽  
Antimitotic Agent ◽  
Proton Abstraction ◽  
Diels Alder Reaction ◽  
Hydrolysis Of

The syntheses of a variety of 3,4-disubstituted pyrroles including the antimitotic agent Verrucarin E are described. 3,4-Pyrroledicarboxylic esters were prepared through a Diels–Alder reaction. Partial hydrolysis of the diesters gave the 4-ester-3-acids which were modified to achieve the synthesis of a variety of unsymmetrically 3,4-disubstituted pyrroles. Raney nickel reduction of a thiolester gave hydroxymethyl under conditions which left acyl or carbalkoxy substituents unaffected. Pyrrole reactions involving carbanionic reagents are complicated by 1-proton abstraction. Therefore, when necessary, the nitrogen was protected by an N-benzyloxymethyl substituent which can be cleaved to the N-hydroxymethyl derivative by aluminum chloride or by hydrogenolysis. Subsequent treatment with benzyltrimethylammonium hydroxide gave back the pyrrole.

scholarly journals Direct Diels-Alder reaction of chitin derived 3-acetamido-5-acetylfuran

2022 ◽  
Author(s):  
Rafael Gomes ◽  
Juliana Pereira ◽  
João Ravasco ◽  
João Vale ◽  
Fausto Queda
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Fine Tuning ◽  
Reduced Form ◽  
Partial Hydrolysis ◽  
Reaction Conditions ◽  
Diels Alder Reaction ◽  
Direct Use ◽  
Kinetics Of ◽  
Hydrolysis Of

The Diels-Alder (DA) reaction of biomass derived furans is an emerging technology for the preparation of new molecular entities and “drop-in” commodity chemicals. In this work we address the challenge of the direct use of electron-poor furanic platforms as dienes through the use of an unexplored chitin derived furan, 3-acetamido-5-acetylfuran (3A5AF). The 3-acetamido group promoted a remarkable increase in the kinetics of the DA allowing for the preparation of 7-oxanorbornenes (7-ONB) at 50 ºC. Partial hydrolysis of the enamide to hemi-acylaminals was possible upon fine tuning of the reaction conditions, disabling retro-DA processes. Finally, DA reaction of the reduced form of 3A5AF allowed quantitative formation of 7-ONB in aqueous condition after 10 minutes. Certanly these are the first steps for expanding the toolbox of chitin derived 3A5AF as diene.

A synthesis and some reactions of 7-Oxabicyclo[2.2.1]heptan-2-one

1983 ◽  
Vol 36 (12) ◽  
pp. 2473 ◽  
Author(s):  
J Moursounidis ◽  
D Wege
Keyword(s):  
Thermal Decomposition ◽  
Alder Reaction ◽  
Diels Alder ◽  
Acid Mixture ◽  
Diels Alder Reaction ◽  
Reaction Proceeds ◽  
Atom Migration ◽  
Acyl Azide ◽  
Mild Hydrolysis ◽  
Hydrolysis Of

Diels-Alder reaction between furan and α-chloroacrylonitrile gives a mixture of exo-2-chloro-and endo-2-chloro-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitrile (4) and (5). Mild hydrolysis affords the corresponding α-chloro acid mixture, from which the endo carboxylic acid may be removed through iodo lactone formation. Catalytic hydrogenation of (4) and (5) followed by hydrolysis, acyl azide formation, Curtius rearrangement, and hydrolysis of the resulting mixture of a-chloro isocyanates yields 7-oxabicyclo[2.2.l]heptan-2-one (1) in preparatively useful amounts. Reduction of (1) gives only endo alcohol, and Baeyer-Villiger reaction proceeds with exclusive bridgehead atom migration. Thermal decomposition of the sodium salt of the p-toluenesulfonylhydrazone of (1) affords 7-oxatricyclo[2.2.1 .02,6]heptane.

Influence of Lewis acids on the Diels–Alder reaction. III. Rearrangement of dimethyl N-carbomethoxy-7-azabicyclo[2.2.1]2,5-heptadiene-2,3-dicarboxylate adducts to dimethyl N-carbomethoxy-3-aminophthalates

1970 ◽  
Vol 48 (9) ◽  
pp. 1472-1474 ◽  
Author(s):  
R. C. Bansal ◽  
A. W. McCulloch ◽  
A. G. McInnes
Keyword(s):  
Aluminum Chloride ◽  
Lewis Acids ◽  
Alder Reaction ◽  
Diels Alder ◽  
Prolonged Treatment ◽  
Dimethyl Acetylenedicarboxylate ◽  
Diels Alder Reaction ◽  
Convenient Route

Aluminum chloride accelerates the Diels–Alder reactions of 2- or 2,5-substituted N-carbomethoxypyrroles with dimethyl acetylenedicarboxylate, and also catalyzes rearrangement of the N-carbomethoxy-7-azanorbornadiene adducts to 6- and 4,6-substituted dimethyl N-carbomethoxy-3-aminophthalates. Aromatization of the corresponding adduct of N-carbomethoxypyrrole only occurs on prolonged treatment with BF3. The procedure promises to be a convenient route for the synthesis of polysubstituted anilines.

Synthesis of bicyclic diones and thiones. Facile methylation of the enolates of bicyclo[2.2.1]heptane-2,5-dione and bicyclo[2.2.2]octane-2,5-dione. An AM1 computational study of bicyclic enolates

1992 ◽  
Vol 70 (3) ◽  
pp. 974-980 ◽  
Author(s):  
N. H. Werstiuk ◽  
S. Yeroushalmi ◽  
Hong Guan-Lin
Keyword(s):  
Raney Nickel ◽  
Good Yield ◽  
Computational Study ◽  
Alder Reaction ◽  
Diels Alder ◽  
Am1 Calculations ◽  
Diels Alder Reaction ◽  
Bicyclic Ketones ◽  
One Step

A group of bicyclic ketones and thiones have been synthesized for homenolization studies. Bicyclo[2.2.1]heptane-2,5-dione (6) undergoes unusually rapid tetramethylation giving 3,3,6,6-tetramethylbicyclo[2.2.1]heptane-2,5-dione (1) in good yield. Treatment of 1 with P2S5 in xylene gave 3,3,6,6-tetramethylbicyclo[2.2.1]heptane-2,5-dithione (2) and 3,3,6,6-tetramethyl 15-oxo-bicyclo[2.2.1]heptane-2-thione (3), which was converted into 4 with Raney nickel. Bicyclo[2,2,2]octane-2,5-dione (7), prepared via a Diels–Alder reaction between 2-trimethylsilyloxy-1,3-cyclohexadiene and and α-acetoxyacrylonitrile followed by a one-step desilylation/hydrolysis, also undergoes facile tetramethylation giving 3,3,6,6-tetramethylbicyclo[2.2.2]octane-2,5-dione (5) in good yield. AM1 calculations were carried out on the α-enolates of bicyclo[2.2.1]heptan-2-one, 6, 5-methylidenebicyclo[2.2.1]heptan-2-one, and 4-acetylbicyclo[2.2.1]-heptan-2-one in an attempt to gain information on the source of the enhanced acidity of the C-3 hydrogens of 6 and 7. Keywords: bicyclic ketones, thiones, synthesis.

scholarly journals New insights into the cross-linking and degradation mechanism of Diels–Alder hydrogels

2015 ◽  
Vol 3 (3) ◽  
pp. 449-457 ◽  
Author(s):  
Susanne Kirchhof ◽  
Andrea Strasser ◽  
Hans-Joachim Wittmann ◽  
Viktoria Messmann ◽  
Nadine Hammer ◽  
...  
Keyword(s):  
Ring Opening ◽  
Degradation Mechanism ◽  
Alder Reaction ◽  
Diels Alder ◽  
Cross Linking ◽  
Diels Alder Reaction ◽  
Maleamic Acid ◽  
The Cross ◽  
Hydrolysis Of

Degradation of Diels–Alder hydrogels occurs by retro-Diels–Alder reaction followed by OH−-catalyzed ring-opening hydrolysis of maleimide groups to unreactive maleamic acid derivatives.

Syntheses of Angucyclinones Related to Ochromycinone. III. An 11-Hydroxy Isomer and Some Reduced Analogues

1999 ◽  
Vol 52 (2) ◽  
pp. 129 ◽  
Author(s):  
Tomas Rozek ◽  
Tomas Rozek ◽  
Dennis K. Taylor ◽  
Dennis K. Taylor ◽  
Edward R. T. Tiekink ◽  
...  
Keyword(s):  
Hydroxy Group ◽  
Alder Reaction ◽  
Diels Alder ◽  
X Ray ◽  
X Ray Crystallography ◽  
Diels Alder Reaction ◽  
Stereo Selectivity ◽  
Hydrolysis Of ◽  
Alder Adduct

The boron triacetate assisted Diels Alder reaction between racemic 5,5-dimethyl-3-vinylcyclohex- 2-enyl acetate and 5-hydroxynaphthoquinone yields the racemic 11-hydroxy-3,3-dimethyl-7,12-dioxo- 1,2,3,4,6,6a,7,12,12a,12b-decahydrobenzo[a]anthracen-1-yl acetate as the sole stereoisomer by regio- and stereo-selective cis endo addition. Aromatization of the Diels Alder adduct followed by hydrolysis of the acetate and oxidation of the resultant 1-hydroxy group gives the target angucyclinone, 11-hydroxy-3,3-dimethyl-1,2,3,4,7,12-hexahydrobenzo[a]anthracene-1,7,12-trione, in an overall yield of 37% from 5-hydroxynaphthoquinone. The regio- and stereo-selectivity of the Diels Alder addition is confirmed by a combination of 13C n.m.r. spectroscopy and X-ray crystallography.

A,B-Diheteropentalenes by a Tandem Intramolecular Diels-Alder/Reverse Diels-Alder Reaction Sequence. Application to the Synthesis of Thieno[3,4-b]furan

1995 ◽  
Vol 48 (3) ◽  
pp. 593 ◽  
Author(s):  
JH Buttery ◽  
J Moursounidis ◽  
D Wege
Keyword(s):  
Furan Ring ◽  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Coupling Constants ◽  
Reaction Sequence ◽  
Acetylenic Ester ◽  
Diels Alder Reaction ◽  
Tricyclic Compound ◽  
Hydrolysis Of

Alkylation of 2-furylmethanethiol (28) with propargyl chloride gave the thioether (22) which on methoxycarbonylation afforded the acetylenic ester (30). On heating, this material underwent an intramolecular Diels -Alder reaction to give the tricyclic compound (32). In the presence of 3,6- di (pyridin-2′-yl)-s- tetrazine , (32) afforded methyl 4,6-dihydrothieno[3,4-b]furan-3-carboxylate (38) by a sequence involving a further Diels -Alder reaction followed by two reverse Diels-Alder reactions. The ester (38) could be dehydrogenated to give methyl thieno [3,4-b]furan-3-carboxylate (40) while hydrolysis of (38), followed by decarboxylation and dehydrogenation delivered the parent thieno [3,4-b]furan (5). 3-Methyl-4,6-dihydrothieno[3,4-b]furan (46) and 3-methylthieno[3,4-b]furan (47) were prepared; a comparison of the 4JMe-C=C-H coupling constants in the 1H n.m.r . spectra of (46) and (47) suggests that an increase in the C2-C3 furyl bond order accompanies the (46) → (47) conversion. Methyl 4,6-dihydrofuro[3,4-b]furan-3-carboxylate (39), 4,6-dihydrofuro[3,4-b]furan (27) and methyl 4,6-dihydro-6-phenylfuro[3,4-b]furan-3-carboxylate (53) were prepared by an analogous tandem reaction sequence. These compounds could not be dehydrogenated to the fully conjugated furo [3,4-b]furan ring system.

Tandem Wessely oxidation and intramolecular Diels–Alder reactions. IV. The synthesis of (±)-coronafacic acid

1993 ◽  
Vol 71 (7) ◽  
pp. 995-1001 ◽  
Author(s):  
Peter Yates ◽  
N.K. Bhamare ◽  
Thierry Granger ◽  
T.S. Macas
Keyword(s):  
Hydrochloric Acid ◽  
Sodium Ethoxide ◽  
Alder Reaction ◽  
Diels Alder ◽  
Lead Tetraacetate ◽  
Oxidative Decarboxylation ◽  
Coronafacic Acid ◽  
Diels Alder Reaction ◽  
Mild Hydrolysis ◽  
Hydrolysis Of

Ethyl E-5-(4-ethyl-2-hydroxyphenyl)-2-pentenoate (7), prepared in four steps from m-ethylphenol (9), was converted via Wessely oxidation with lead tetraacetate followed by intramolecular Diels–Alder reaction in boiling xylene to ethyl 1-acetyloxy-6-ethyl-2,3,3a,4,5,7a-hexahydro-8-oxo-1,5-methano-1H-indene-anti-4-carboxylate (16). Hydrogenation of 16 followed by mild hydrolysis gave ethyl 6-ethyloctahydro-1-hydroxy-8-oxo-1,5-methano-1H-indene-anti-4-car-boxylate (24), which on oxidation with periodate gave 4-(ethoxycarbonyl)-6-ethyloctahydro-1-oxo-1H-indene-5-car-boxylic acid (26). Oxidative decarboxylation of this gave a mixture of ethyl 6-ethyl-2,3,3a,6,7,7a-hexahydro-1-oxo-1H-indene-4-carboxylate (31) and ethyl 6-ethyl-2,3,3a,4,7,7a-hexahydro-1-oxo-1H-indene-4-carboxylate (32); the latter was converted to the former by ethanolic sodium ethoxide. Hydrolysis of 31 with hot hydrochloric acid gave (±)-coronafacic acid (4).

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