The Pyrolysis of Phenylnaphthalenedicarboxylic Anhydrides: Products of Ring Contraction and of Radical Cyclization

1990 ◽  
Vol 43 (7) ◽  
pp. 1137 ◽  
Author(s):  
MR Anderson ◽  
RFC Brown ◽  
KJ Coulston ◽  
FW Eastwood ◽  
A Ward
Keyword(s):  
Major Product ◽  
Radical Cyclization ◽  
Diels Alder ◽  
Ring Contraction ◽  
Step Process ◽  
Flash Vacuum Pyrolysis ◽  
Cyclization Process ◽  
Vacuum Pyrolysis ◽  
One Step

Naphthalene-1,2,-dicarboxylic anhydrides with neighbouring phenyl substituents give on flash vacuum pyrolysis (850-900°/0.02-0.04 mm) ring-contracted carbenes which insert into the phenyl groups. The 8- phenyl anhydride (7) gives acephenanthrylene (10) as the major product, and the 3-phenyl anhydride (15) gives 1,2 : 4,5-dibenzopentalene (indeno [2,1-a]indene) (18). The anhydrides (7) and (15) were � synthesized by pyrolysis of the corresponding 1-naphthylmethyl propynoates (2) and (13) through a new one-step process of intramolecular Diels -Alder addition/retro-Diels -Alder elimination of acetylene. 1-Phenylnaphthalene-2,3-dicarboxylic anhydride (19) on pyrolysis at 960°/0.02 mm gives fluoranthene (11) as the major product. The behaviour of the 1-C6D5 compound (24) suggests involvement of a radical cyclization process.

Some reactions of 2-ethenyl-4,4-Ethylenedioxy-1-methylcyclohex-1-ene prepared by pyrolysis of 5,5-Ethylenedioxy-7a-methyl-4,5,6,7-tetrahydro-2H-inden-1(7aH)-one

1984 ◽  
Vol 37 (11) ◽  
pp. 2295 ◽  
Author(s):  
RFC Brown ◽  
GL Burge ◽  
DJ Collins
Keyword(s):  
High Pressures ◽  
Preparative Thin Layer Chromatography ◽  
Major Product ◽  
Diels Alder ◽  
Lewis Acid Catalysts ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Layer Chromatography ◽  
Mild Hydrolysis ◽  
Hydrolysis Of

Flash vacuum pyrolysis of 5,5-ethylenedioxy-7a-methyl-4,5,6,7-tetrahydro-2H-inden-1(7aH)-one (2) at 630� gave a good yield of 2-ethenyl-4,4-ethylenedioxy-1-methylcyclohex-1-ene (6), but at 740� p-cresol was the major product. The diene acetal (6) was also obtained by pyrolysis of 5,5-ethylene- dioxy-lβ-hydroxy-7a-methyl-1,2,5,6,7,7a-hexahydro-4H-indene-1α-carbonitrile (3) at 600�. Pyrolytic reactions of 7a-methyl-2,3,7,7a-tetrahydro-1H-indene-1,5(6H)-dione (1), 5,5-ethylenedithio-7a- methyl-2,3,5,6,7,7a-hexahydro-1H-inden-1-one (7) and of 1,1-ethylenedioxy-3,5,5-trimethylcyclohex- 3-ene (8) are also described. Mild hydrolysis of the diene acetal (6) afforded 3-ethenyl-4-methylcyclohex-3-en-1-one (9) which upon brief treatment with dry hydrogen chloride in chloroform at 0� gave, after preparative thin-layer chromatography, a low yield of pure 3-ethenyl-4-methylcyclohex-2-en-1-one (11). The diene acetal (6) failed to undergo Diels-Alder reactions, even at high pressures with Lewis acid catalysts, and it reacted anomalously with two molecules of 4-phenyl-1,2,4-triazoline-3,5-dione; the isomeric diene acetal 1-ethenyl-3,3-ethylenedioxy-6-methylcyclohex-1-ene (18) gave the expected Diels-Alder adduct with this reagent.

New Thermal and Photochemical Routes to Dewar Furan and Other Isomers on the C4H4O Energy Surface: the Role of Isobenzofuran as a Trapping Agent

1991 ◽  
Vol 44 (9) ◽  
pp. 1275 ◽  
Author(s):  
RN Warrener ◽  
IG Pitt ◽  
RA Russell
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Energy Surface ◽  
Thermal Study ◽  
Diels Alder ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Benzene Oxide ◽  
Trapping Agent

Photolysis of the specially synthesized substrate (39) leads to quantitative fragmentation into the phthalimide (56) and Dewar furan (4a). Dewar furan has only transient existence even at -65°, yet can be trapped effectively with isobenzofuran but not furan. Rapid isomerization to cycloprop-2-enecarbaldehyde (57) occurs at the photolysis temperatures and this product is also trapped by the isobenzofuran . In the absence of trapping agent, photolysis of (39) produces some furan but no 1H n.m.r . evidence can be obtained for (4a) or (57), even at low temperatures (-85°). Separate irradiation of (57) causes extensive polymerization, without yielding other recognizable products. Furan is concluded, therefore, to arise from photoisomerization of (4a) rather than photochemical or thermal isomerization of (57). Separate thermal study of (57) shows that isomerization to furan only occurs above 420°. Flash vacuum pyrolysis of the polycyclic epoxide (72) provides a new retro- Diels-Alder route to (57) which likely proceeds via (4a) as an intermediate. At high temperatures (57) is isomerized to furan. A new Dewar benzene oxide (41) and Dewar benzene (45) are reported en route to the photosubstrates (39) and (50) respectively. Photolysis of (50) provides a high-yielding source of cyclobutadiene , which in the absence of trapping agent yields the syn-dimer (59).

ChemInform Abstract: Tandem Radical Cyclization in the Flash Vacuum Pyrolysis of 2- Methoxyphenyl and 2-Methylthiophenyl Substituted Phosphorus Ylides.

ChemInform ◽  
2010 ◽  
Vol 26 (33) ◽  
pp. no-no
Author(s):  
R. A. AITKEN ◽  
C. K. BRADBURY ◽  
G. BURNS ◽  
J. J. MORRISON
Keyword(s):  
Radical Cyclization ◽  
Phosphorus Ylides ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Preparation of the First Isobenzofuran Containing Two Ring Nitrogens: A New Diels - Alder Diene for the Synthesis of Molecular Scaffolds Containing One or More End-Fused 3,6-Di(2-pyridyl)pyridazine Ligands

2003 ◽  
Vol 56 (8) ◽  
pp. 811 ◽  
Author(s):  
Ronald N. Warrener ◽  
Douglas N. Butler ◽  
Davor Margetic
Keyword(s):  
Diels Alder ◽  
Molecular Scaffolds ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Ring Nitrogen ◽  
Molecular Architectures ◽  
First Time

Preparation of a stable, crystalline isobenzofuran containing two ring-nitrogen atoms, 4,7-di(2-pyridyl)-5,6-diazaisobenzofuran (diaza-IBF) (12), is reported here for the first time. Diaza-IBF was prepared using the s-tetrazine-induced fragmentation of 1,4-di(2-pyridyl)-5,8-epoxy-5,8-dihydrophthalazine (9), for which a synthesis is provided. Diaza-IBF was also prepared by flash vacuum pyrolysis (FVP) of the isomeric N-methyl-1,4-di(2-pyridyl)-5,8-epoxy-5,6,7,8-tetrahydrophthalazine-6,7-dicarboximides (18) and (19), formed in three steps from furan, N-methyl maleimide, and 3,6-di(2-pyridyl)-s-tetrazine. Diaza-IBF was employed in cycloaddition protocols with alkenes to form scaffold mono- or bis-3,6-di-(2-pyridyl)-pyridazine ligands having novel molecular architectures.

Flash Vacuum Pyrolysis of [2,3-13C2]Triphenylene-2,3-dicarboxylic Anhydride: Formation of Labelled Cyclopent[hi]acephenanthrylene and Triphenylene

1997 ◽  
Vol 50 (12) ◽  
pp. 1183 ◽  
Author(s):  
Roger F. C. Brown, ◽  
Karen J. Coulston ◽  
Frank W. Eastwood
Keyword(s):  
Major Product ◽  
Principal Product ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis (f.v.p.) of [2,3-13C2]triphenylene-2,3-dicarboxylic anhydride (c. 22·5% 13C2) at 950°C gave a pyrolysate which was analysed by 13C n.m.r. spectroscopy. The principal product was [2,3-13C2]triphenylene. The second major product was a 1 : 2 : 1 mixture of [4,7- 13C2]-, [4,6-13C2]- and [5,6-13C2]-cyclopent[hi]acephenanthrylene.

scholarly journals Syntheses of Combretastatins D-1, D-2, and D-4 via Ring Contraction by Flash Vacuum Pyrolysis

2016 ◽  
Vol 82 (1) ◽  
pp. 579-587 ◽  
Author(s):  
Marina Harras ◽  
Wolfgang Milius ◽  
R. Alan Aitken ◽  
Rainer Schobert
Keyword(s):  
Ring Contraction ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis of anthracenic Diels–Alder adducts, a convenient source of methanethial and methanethial S-oxide

1987 ◽  
Vol 65 (2) ◽  
pp. 290-291 ◽  
Author(s):  
Yannick Vallee ◽  
Jean-Louis Ripoll ◽  
Christophe Lafon ◽  
Geneviève Pfister-Guillouzo
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Low Temperature ◽  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Diels Alder ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Nuclear Magnetic

The flash vacuum pyrolysis of Diels–Alder adducts of anthracene constitutes a rapid and selective route to methanethial 1 and methanethial S-oxide 2, as analyzed in the gas phase by photoelectron spectroscopy. Low temperature infrared and nuclear magnetic resonance (1H, 13C) spectra are also reported for sulfine 2.

ChemInform Abstract: Retro-Diels-Alder Fragmentation of 2,5,6-Triphenyl-3,4- didehydropyridine Generated by Flash Vacuum Pyrolysis at 900°C.

ChemInform ◽  
2010 ◽  
Vol 23 (52) ◽  
pp. no-no
Author(s):  
R. F. C. BROWN ◽  
N. CHOI ◽  
F. W. EASTWOOD
Keyword(s):  
Diels Alder ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis
Sign in / Sign up

Export Citation Format

Share Document