
%0 Journal Article
%A Brown, RFC 
%A Eastwood, FW 
%A Chaichit, N 
%A Gatehouse, BM 
%A Pfeiffer, JM 
%A Woodroffe, D 
%T Methyleneketenes and methylenecarbenes. XVI. The formation of Diphenylfuran-2-ones and 3-Phenylphthalide as minor products of the pyrolysis of diphenylmethyl propiolate
%J Australian Journal of Chemistry
%D 1981/07/01
%V 34
%N 7
%P 1467-1481
%K 
%R https://doi.org/10.1071/CH9811467
%U https://www.publish.csiro.au/paper/CH9811467 
%X The formation of a mixture of lactones as a minor product of the flash vacuum pyrolysis of diphenyl-methyl propiolate (1) has been investigated further.     The diphenylfuran-2-ones (3), (4), and (5) are shown to be formed through an intramolecular insertion reaction of the methylenecarbene (2), formed from (1) at 640&#176;, which leads to 5,5-diphenyl-furan-2(5H)- one (3) as the primary product.     3-Phenylphthalide (8) is apparently formed by intramolecular Diels-Alder addition of the C&#8801;C bond of (1) to one phenyl ring which acts as the diene component, followed by loss of acetylene from an intermediate barrelene derivative (10). This is confirmed by a deuterium labelling experiment.     1-Phenyl-2-benzoxepin-3(1H)-one (7), considered at first as a possible intermediate in the pyrolysis of (1), is synthesized in six steps from 2-aminobenzophenone, and its X-ray structure determination is reported. On pyrolysis at 640&#176;/0.07 mm (7) decarbonylates smoothly to give 2-vinylbenzophenone. 
