79692-08-3Relevant academic research and scientific papers
Methyleneketones and Methylenecarbenes. XVI. The Formation of Diphenylfuran-2-ones and 3-Phenylphthalide as Minor Products of the Pyrolysis of Diphenylmethyl Propiolate
Brown, Roger F. C.,Eastwood, Frank W.,Chaichit, Narongsak,Gatehouse, Bryan M.,Pfeiffer, Jan M.,Woodroffe, David
, p. 1467 - 1481 (2007/10/02)
The formation of a mixture of lactones as a minor product of the flash vacuum pyrolysis of diphenylmethyl 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 deg, which leads to 5,5-diphenylfuran-2(5H)-one (3) as the primary product. 3-Phenylphthalide (8) is apparently formed by intramolecular Diels-Alder addition of the CC 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 deg/0.07 mm (7) decarbonylates smoothly to give 2-vinylbenzophenone.
