Methyleneketenes and methylenecarbenes. XI. Rearrangements of cycloalkylidenecarbenes

1978 ◽  
Vol 31 (2) ◽  
pp. 327 ◽  
Author(s):  
GJ Baxter ◽  
RFC Brown
Keyword(s):  
Diels Alder ◽  
Ring Size ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

The products of flash vacuum pyrolysis of the cycloalkylidene derivatives (3) of Meldrum's acid at 480-640° are rationalized in terms of formation of the cycloalkylidenecarbenes (1; ring size n = 4-8)and their rearrangement to cycloalkynes, to bicyclic cyclopropenes (e.g. (7)), or to further products derived from these. Pyrolysis of the 3,3-dimethylcyclobutylidene derivative (3h) gave 3,5-dimethylphenol, probably formed by cyclization of the (Z)-hexatrienone (22). ��� The tetrahydrofuran-3-ylidene derivative (3i) gave butatriene and formaldehyde as major products of pyrolysis; these may be formed by retro-Diels-Alder fission of the heterocycloalkyne (27).

A Pyrolytic Approach to 2-Hydroxy-7-methoxy-5-methyl-1-naphthoic Acid

1995 ◽  
Vol 48 (5) ◽  
pp. 1055 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
JM Horvath
Keyword(s):  
Carboxylic Acid ◽  
Condensation Product ◽  
Quantitative Yield ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Title 1 ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Naphthoic Acid

Condensation of 4-methoxy-2,6-dimethylbenzaldehyde with Meldrum's acid, and flash vacuum pyrolysis of the condensation product (12) gave in almost quantitative yield 7-methoxy-5-methyl-2-naphthol (9). This naphthol is a precursor of the title 1-carboxylic acid (6), an intercalating moiety of enediyne and other antibiotics.

Methyleneketenes and methylenecarbenes. XV. A new synthesis of ruscodibenzofuran

1980 ◽  
Vol 33 (8) ◽  
pp. 1817 ◽  
Author(s):  
RFC Brown ◽  
CM Jones
Keyword(s):  
Condensation Product ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
New Synthesis

Ruscodibenzofuran (2-acetyl-6,9-dimethyldibenzofuran-3-ol) has been synthesized by condensation of 2,4,7-trimethylbenzofuran-3-carbaldehyde with Meldrum's acid, flash vacuum pyrolysis of the condensation product (8), and overall C-acetylation of the resulting 6,9-dimethylbenzofuran- 3-ol.

Cyclopentadienylideneethenone: Pyrolytic Generation and Argon Matrix Infrared Spectroscopic Study

1989 ◽  
Vol 42 (8) ◽  
pp. 1321 ◽  
Author(s):  
RFC Brown ◽  
NR Browne ◽  
KJ Coulston ◽  
FW Eastwood ◽  
MJ Irvine ◽  
...  
Keyword(s):  
Carbonyl Group ◽  
Alder Reaction ◽  
Infrared Spectroscopic Study ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Argon Matrix ◽  
Flash Vacuum Pyrolysis ◽  
Matrix Isolation Spectroscopy ◽  
Vacuum Pyrolysis ◽  
Argon Matrices

Two previously reported pyrolytic precursors for cyclopentadienylideneethenone (4) and benzyne produced two strong infrared bands attributable to ketene type compounds when their pyrolysates were examined by argon matrix isolation spectroscopy. To determine which band should be assigned to (4), four new precursors for (4) and benzyne and two analogues labelled with 13C at the carbonyl group have been synthesized. Precursors (8) and (14) are respectively a caged system and a bridged ,system bearing a mixed anhydride with trifluoroacetic acid. Flash vacuum pyrolysis of (8) and (14) at 600-700 with trapping at 77 K gave pyrolysates which contained biphenylene. Pyrolysis of (8) and (14) at 600-700�; in a stream of argon followed by deposition as an argon matrix at about 10 K showed that both produced a pyrolysate absorbing at 2089 cm-1 assigned to (4). Precursors (24) and (25) and the previously reported (18) and (27) are Meldrum's acid derivatives designed to yield the hypothetical cyclopentadienylidene Meldrum's acid (19) by cage fission or retro-Diels-Alder reaction. They all gave their biphenylene on flash vacuum pyrolysis at 600-700 � and their pyrolysates in argon matrices showed absorption both at 2089 cm-1 due to (4) and at 2225 cm-1 due to an unidentified ketene. The frequency shift resulting from substitution of 13C in the carbonyl group (52 cm-l) is in accordance with the assignment of the 2089 cm-1 band to (4). The pyrolysates from precursors 8a), (14), (18a), (25)and (27) were allowed to react with methanol and the resulting mixtures were hydrogenated. In all cases methyl cyclopentylacetate was obtained.

Efficient synthesis of acetylated bicyclic [n.3.0] hydroxypyrroles from cyclic lactams via flash vacuum pyrolysis of Meldrum's acid derivatives

1988 ◽  
Vol 53 (24) ◽  
pp. 5680-5685 ◽  
Author(s):  
Jean Claude Pommelet ◽  
Hamid Dhimane ◽  
Josselin Chuche ◽  
Jean Pierre Celerier ◽  
Mansour Haddad ◽  
...  
Keyword(s):  
Efficient Synthesis ◽  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Meldrum's Acid Derivatives

Pyrolytic Generation of 3-Phenylindol-2-ylmethylene-carbene and Its Cyclization to 7H-Benzo[c]carbazole

1994 ◽  
Vol 47 (2) ◽  
pp. 411 ◽  
Author(s):  
RFC Brown ◽  
KJ Coulston ◽  
FW Eastwood ◽  
JJ Manyweathers
Keyword(s):  
Meldrum's Acid ◽  
Meldrum’S Acid ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis

Flash vacuum pyrolysis of the 3-phenylindol-2-ylmethylene derivative (12) of Meldrum's acid at 600° and at 750°/0.03 mm gives 9-phenyl-3H-pyrrolo[1,2-a]indol-3-one (14) (97%). At 900°/0.3 mm (14) (49%) is accompanied by 7H-benzo[c] carbazole (6) (10%). The latter is formed by intramolecular C-H insertion in the title carbene (5).

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