- Syntheses and pyrolyses of benzofuran analogues of α-oxo-o- quinodimethane. A study on vinylcarbene-cyclopropene rearrangement
-
(Chemical Equation Presented) Flash vacuum pyrolyses (FVP) of benzoic 3-methyl-2-benzofurancarboxylic anhydride (12) and benzoic 2-methyl-3- benzofurancarboxylic anhydride (13) at 550°C and ca. 10-2 torr both give methylenebenzocyclobutenone (21) as the major product and indenone (22) as the minor one. A mechanism involving generation of α-oxo-o- quinodimethane 11 as the primary pyrolysis product from FVP of 13, followed by elimination of a CO molecule to give carbene 24, which undergoes a vinylcarbene-cyclopropene rearrangement and a ring contraction of the resulting carbene 23, is proposed to account for the observed results. The proposed mechanism is further supported by a deuterium-labeling study on FVP of (2-benzofuryl)methyl-α,α-d2 benzoate (28-d2).
- Tseng, Pen-Wen,Yeh, Su-Wen,Chou, Chin-Hsing
-
p. 3481 - 3485
(2008/09/21)
-
- Study of the pyrolytic chemistry of isobenzofurylmethyl benzoates
-
Pyrolysis of (1-isobenzofuryl)methyl benzoate (9a), produced in situ from flash vacuum pyrolysis of (7-oxa-1-benzonorbornenyl)methyl benzoate (10a), gave methylenebenzocyclobutenone (4), 2-ethynylbenzaldehyde (5) and benzocyclopentadienone (6). The deuterium-labeled study indicated that the mechanism for the formation of these products involved the double migrations of benzoate group in 9a. Pyrolysis of (3-methyl-1-isobenzofuryl)methyl benzoate (9c) gave 1,3-dimethylene-1,3-dihydroisobenzofuran (33), which is stable in benzene and hydrolyzed rapidly in chloroform to give 1,2-diacetylbenzene (35).
- Chen, Ping-Shu,Chou, Chin-Hsing
-
p. 17115 - 17126
(2007/10/03)
-