
TY  - JOUR
A1  - Crow, WD 
A1  - Paddon-Row, MN 
T1  - The C<sub>7</sub>H<sub>6</sub> energy surface: phenylcarbene and 2-Methylene-3,5-cyclohexadienylidene&#8211;A duality of mechanism
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1973
VL  - 26
IS  - 8
SP  - 1705
EP  - 1723
KW  - 
UR  - https://doi.org/10.1071/CH9731705 
N2  - The conversion of phenylcarbene (1) into fulvenallene (17) and ethynylcyclo-pentadiene (18) on gas-phase pyrolysis has been examined by 13C-tracer techniques. Complete randomization of all seven carbon atoms has been shown to precede ring contraction. The result is consistent with a pool of intermediates [cycloheptatrienylidene (19) and bicyclo[4,1,0]hepta-2,4,6-triene (21)], interconverting rapidly through tautomerism and concomitant H-shifts. Dimerization, intramolecular trapping, and ring contraction constitute the major exits from this pool.     Gas-phase thermolysis of indazole generates the same products (17)/(18) and in this case the mechanism has been investigated by the intramolecular trapping in 1-deutero-3-methylindazole to yield deuterostyrenes. Two pathways are revealed, proceeding respectively through phenylcarbene and 2-methylene-3,5-cyclohexadienyl-idene (36); factors affecting the latter pathway are discussed. 
ER  -

