Flash vacuum pyrolysis. VII. Fulvenallene. The ring contraction and expansion of phenylcarbene

1970 ◽  
Vol 92 (7) ◽  
pp. 2147-2149 ◽  
Author(s):  
Paul. Schissel ◽  
M. E. Kent ◽  
David J. McAdoo ◽  
Eddie. Hedaya
Keyword(s):  
Ring Contraction ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Contraction And Expansion

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 Phenanthrene-3,4-dicarboxylic Anhydride and of Cyclobuta[c]-phenanthrene-1,2-dione: Products of Ring Contraction, Insertion and Ring Cleavage

1991 ◽  
Vol 44 (7) ◽  
pp. 967 ◽  
Author(s):  
M Adeney ◽  
RFC Brown ◽  
KJ Coulston ◽  
FW Eastwood ◽  
IW James
Keyword(s):  
Ring Cleavage ◽  
Reaction Sequence ◽  
Ring Contraction ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Carbene Insertion ◽  
Highly Strained

Flash vacuum pyrolysis of phenanthrene-3,4-dicarboxylic anhydride and of cyclobuta [c]phenanthrene-1,2-dione (860-70°/0.02-0.04 mm) gave a pyrolysate containing 1-ethynylacenaphthylene, 3-ethynylacenaphthylene and phenanthrene. The identity of the two ethynes was confirmed by synthesis. The results are interpreted in terms of a reaction sequence involving aryne formation, ring contraction, carbene insertion and ring cleavage of a highly strained intermediate.

Formation of Cyclopent[a]indene and Acenaphthylene from Allyl Esters of Biphenyl Mono- and Di-carboxylic Acids and from Biphenyl Dicarboxylic Anhydrides on Flash Vacuum Pyrolysis at 1000 - 1100°C

1997 ◽  
Vol 50 (12) ◽  
pp. 1159 ◽  
Author(s):  
Jayant B. Bapat, ◽  
Roger F. C. Brown ◽  
Glenn H. Bulmer, ◽  
Trevor Childs, ◽  
Karen J. Coulston ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Ring Contraction ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Allyl Esters

Flash vacuum pyrolysis at 1000-1100°C of the allyl esters of the three isomeric biphenylcarboxylic acids, of the allyl esters of the 12 biphenyldicarboxylic acids and of the three biphenyldicarboxylic anhydrides gave pyrolysates which were examined by 1H n.m.r. spectroscopy at temperatures below -50°C. In all cases the spectra showed the presence of cyclopent[a]indene and acenaphthylene together with other products. Possible mechanisms for these ring contraction and cyclization processes are discussed and the results of pyrolyses of [2,3-13C2] biphenyl-2,3-dicarboxylic anhydride, and [3,4-13C2]- and (2-2 H1)-biphenyl-3,4-dicarboxylic anhydrides are reported.

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.

Sulfonyl isocyanides RSO2NC

2017 ◽  
Author(s):  
Curt Wentrup ◽  
Horst Briehl
Keyword(s):  
Ir Spectrum ◽  
Reaction Conditions ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis (FVP) of 5-azido-1-aryltetrazoles results in triple N<sub>2</sub> elimination and formation of aryl isocyanides RNC, which rearrange in part to aroylnitriles RCN under the reaction conditions. Similar FVP of 5-azido-1-arenesulfonyltetrazoles generates a compound absorbing in the IR spectrum (77 K) at 2090 cm<sup>-1 </sup>and assigned the structure of arenesulfonyl isocyanide, ArSO<sub>2</sub>NC <b>11</b>. FVP at temperatures above 600 <sup>o</sup>C results in progressively more nitrile ArSO<sub>2</sub>CN <b>12</b>. Compound <b>11</b> also disappears on warming above -80 <sup>o</sup>C

Sulfonyl isocyanides RSO2NC

2017 ◽  
Author(s):  
Curt Wentrup ◽  
Horst Briehl
Keyword(s):  
Ir Spectrum ◽  
Reaction Conditions ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis (FVP) of 5-azido-1-aryltetrazoles results in triple N<sub>2</sub> elimination and formation of aryl isocyanides RNC, which rearrange in part to aroylnitriles RCN under the reaction conditions. Similar FVP of 5-azido-1-arenesulfonyltetrazoles generates a compound absorbing in the IR spectrum (77 K) at 2090 cm<sup>-1 </sup>and assigned the structure of arenesulfonyl isocyanide, ArSO<sub>2</sub>NC <b>11</b>. FVP at temperatures above 600 <sup>o</sup>C results in progressively more nitrile ArSO<sub>2</sub>CN <b>12</b>. Compound <b>11</b> also disappears on warming above -80 <sup>o</sup>C

The Pyrolytic Rearrangement of 1-Alkynoyl-3-methylpyrazoles: Synthesis of Pyrazolo[1,5-a]pyridin-5-ols and Related Compounds

1994 ◽  
Vol 47 (6) ◽  
pp. 991 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
GD Fallon ◽  
SC Lee ◽  
RP Mcgeary
Keyword(s):  
Carbon Chain ◽  
Ring Structure ◽  
High Yield ◽  
Methyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Fused Ring ◽  
Related Compounds

Flash vacuum pyrolysis of 1-(alkyn-2′-oyl)-3-methylpyrazoles at 650°/0.03 mm forms pyrazolo[1,5-a]pyridin-5-ols, often in high yield, which may bear substituents at C2, C3 or C7. In the absence of a 3-methyl group in the precursor, N-ethynylpyrazoles are formed in low yield. The formation of both types of product is interpreted as involving 3-(N-pyrazolyl)propadienones formed by N1 → N2 migration of the N-alkynoyl group with inversion of the three-carbon chain. The fused-ring structure of 2-methylpyrazolo[1,5-a]pyridin-5-ol (25) was established by X-ray crystallography of the O-benzoyl derivative (27).

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