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.

Transposition of Aromaticity from a Furan to a Cyclohexane Ring in Furoisoindoles During the Interaction of 3-(Furyl)allylamines with Bromomaleic Anhydride

Synlett ◽  
2020 ◽  
Vol 31 (03) ◽  
pp. 255-260
Author(s):  
Kseniia A. Alekseeva ◽  
Elizaveta A. Kvyatkovskaya ◽  
Eugeniya V. Nikitina ◽  
Vladimir P. Zaytsev ◽  
Svetlana M. Eroshkina ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Furan Ring ◽  
Alder Reaction ◽  
Diels Alder ◽  
Cyclohexane Ring ◽  
Reaction Sequence ◽  
Diels Alder Reaction ◽  
Furan Moiety ◽  
Formation Step

An unexpected four-step reaction sequence was discovered in the course of investigation of the interaction between 3-(furan-2-yl)allylamines and bromomaleic anhydride. This conversion begins with the initial N-acylation of the allylamines by the anhydride, followed by intramolecular Diels–Alder reaction, which is accompanied by a dehydrohalogenation, and ends with the formation of partially unsaturated furo[2,3-f]isoindoles followed by transposition of aromaticity from the furan moiety to the neighboring cyclohexane ring. The reaction between 3-(furan-3-yl)allylamines and bromomaleic anhydride does not stop at a furo[2,3-f]isoindole formation step, but proceeds further with the cleavage of the furan ring in a 100% atom-efficient fashion to provide polysubstituted isoindoline-4-carboxylic acids.

scholarly journals Crystal structures and conformations of two Diels–Alder adduct derivatives: 1,8-bis(thiophen-2-yl)-14-oxatetracyclo[6.5.1.02,7.09,13]tetradeca-2(7),3,5-trien-10-one and 1,8-diphenyl-14-oxatetracyclo[6.5.1.02,7.09,13] tetradeca-2,4,6-trien-10-one

2015 ◽  
Vol 71 (2) ◽  
pp. 213-216
Author(s):  
S. Gopinath ◽  
P. Narayanan ◽  
K. Sethusankar ◽  
Meganathan Nandakumar ◽  
Arasambattu K. Mohanakrishnan
Keyword(s):  
Crystal Packing ◽  
Rotation Axis ◽  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Compound I ◽  
Diels Alder Reaction ◽  
Phenyl Rings ◽  
Axis Parallel ◽  
Alder Adduct

The title compounds, C21H16O2S2(I) and C25H20O2(II), are products of a tandem `pincer' Diels–Alder reaction consisting of [2 + 2] cycloadditions between benzo[c]furan and cyclopentanone. Each comprises a fused tetracyclic ring system containing two five-membered rings (inenvelopeconformations with the O atom as the flap) and six-membered rings (inboatconformations). In addition, two thiophene rings in (I) and two phenyl rings in (II) are attached to the tetracyclic ring system. The cyclopentanone ring adopts atwistedconformation in (I) and anenvelopeconformation in (II). In (I), the thiophene rings are positionally disordered over two sets of sites, with occupancy ratios of 0.901 (2):0.099 (2) and 0.666 (2):0.334 (2). In (II), the oxygen atom of the cyclopentanone ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4). The molecular structure of (I) is stabilized by an intramolecular C—H...O hydrogen bond, which generates anS(7) ring motif. In the crystal, the molecules are linkedviaweak C—H...O hydrogen bonds, which generateR22(16) ring motifs in (I) andC(8) chains in (II). In both structures, the crystal packing also features C—H...π interactions. The crystal studied of compound (I) was twinned by non-merohedry. The twin component is related by the twin law [−1 0 0 −0.101 1 −0.484 0 0 −1] operated by a twofold rotation axis parallel to thebaxis. The structure of (I) was refined with a twin scale factor of 0.275 (2).

Synthesis of 2,3-Di- and 2,3,4-Trisubstituted Furans from 1,2-Dioxines Generated by an Enyne-RCM/Diels−Alder Reaction Sequence

2005 ◽  
Vol 70 (17) ◽  
pp. 6995-6998 ◽  
Author(s):  
Young-Keun Yang ◽  
Jung-Hoon Choi ◽  
Jinsung Tae
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Reaction Sequence ◽  
Diels Alder Reaction ◽  
Trisubstituted Furans

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.

ChemInform Abstract: A Facile Synthetic Method of ABCD Ring System of Antitumor Alkaloid Camptothecin via Intramolecular Hetero Diels-Alder Reaction.

ChemInform ◽  
2010 ◽  
Vol 31 (25) ◽  
pp. no-no
Author(s):  
Masahiro Toyota ◽  
Chiyo Komori ◽  
Masataka Ihara
Keyword(s):  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Synthetic Method ◽  
Diels Alder Reaction

scholarly journals NbCl5 as Catalyst in Diels-Alder Reaction of Furan Ring

2013 ◽  
Author(s):  
Deborah A. dos Santos ◽  
Ludmila R. Rodrigues ◽  
Valdemar Lacerda Jr. ◽  
Sandro J. Greco ◽  
Alvaro C. Neto ◽  
...  
Keyword(s):  
Furan Ring ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction

Domino intermolecular and intramolecular Diels-Alder reaction sequence for expedient construction of a pentacyclic framework

2020 ◽  
Vol 28 ◽  
pp. 100404
Author(s):  
K.M. Nishad ◽  
C.S. Aswathi ◽  
P.A. Unnikrishnan ◽  
T.S. Saumya
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Reaction Sequence ◽  
Diels Alder Reaction
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