Flash vacuum pyrolysis of trifluoromethylated diphenyldiazomethanes. Role of trifluoromethyl group in the arylcarbene rearrangement

1997 ◽  
pp. 1745-1746 ◽  
Author(s):  
Hideo Tomioka ◽  
Kohji Taketsuji
Keyword(s):  
Trifluoromethyl Group ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

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).

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

Flash Vacuum Pyrolysis of Isoxazoles, Pyrazoles and Related Compounds

2004 ◽  
Vol 8 (12) ◽  
pp. 1071-1088 ◽  
Author(s):  
G. Yranzo ◽  
E. Moyano
Keyword(s):  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Related Compounds

Preparation of furanoradialene by the flash vacuum pyrolysis of diesters of 3,4-bis(hydroxymethyl)-2,5-dimethylfuran

1984 ◽  
Vol 106 (26) ◽  
pp. 8197-8201 ◽  
Author(s):  
Walter S. Trahanovsky ◽  
Timothy J. Cassady
Keyword(s):  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

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).

Preparation of benzocyclobutenes by flash vacuum pyrolysis

1978 ◽  
Vol 19 (46) ◽  
pp. 4569-4572 ◽  
Author(s):  
Peter Schiess ◽  
Markus Heitzmann ◽  
Suzanne Rutschmann ◽  
René Stäheli
Keyword(s):  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Enones with strained double bonds. 10. Use of flash vacuum pyrolysis to obtain bicyclo[3.3.1]non-1-en-3-one

1987 ◽  
Vol 52 (12) ◽  
pp. 2474-2481 ◽  
Author(s):  
Kay Ann Campbell ◽  
Herbert O. House ◽  
Bruce W. Surber ◽  
Walter S. Trahanovsky
Keyword(s):  
Double Bonds ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis
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