95475-19-7Relevant articles and documents
Synthesis of Precursors of C4 and C5 Cumulenones
Brown, Roger F. C.,Coulston, Karen J.,Eastwood, Frank W.,Gatehouse, Bryan M.,Guddatt, Luke W.,et al.
, p. 2509 - 2524 (2007/10/02)
Bicyclohept-5-en-2-one was condensed with 2,2-dimethyl-1,3-dioxan-4,6-dione in the presence of titanium tetrachloride/pyridine to yield 5-(bicyclohept-5'-en-2'-ylidene)-2,2-dimethyl-1,3-dioxan-4,6-dione (6a) which on pyrolysis at 520-560 deg/0.01 mm gave acetone, carbon dioxide, cyclopentadiene and butatrienone.In the same way 5-(7'-oxabicyclohept-5'-en-2'-ylidene)-2,2-dimethyl-1,3-dioxan-4,6-dione (6b) was prepared from 7-oxabicyclohept-5-en-2-one and on pyrolysis at 570 deg/0.01 mm it gave acetone, carbon dioxide, furan and butatrienone.Alkylation of 2-trimethylsiloxybicyclohepta-2,5-diene with phenylthiomethyl chloride with titanium tetrachloride as catalyst followed by condensation with 2,2-dimethyl-1,3-dioxan-4,6-dione gave an endo/exo mixture of 5-(3'-phenylthiomethylbicyclohept-5'-en-2'-ylidene)-2,2-dimethyl-1,3-dioxan-4,6-dione.The structure of the endo isomer was established by X-ray crystallography.Oxidation of the phenylthiomethyl compound with m-chloroperbenzoic acid yielded the sulfoxide which was converted by boiling in carbon tetrachloride into 5-(3'-methylenebicyclohept-5'-en-2'-ylidene)-2,2-dimethyl-1,3-dioxan-4,6-dione (8).Preliminary studies on the fragmentation of compound (8) have shown that at 450 deg/0.01 mm it is converted into acetone, carbon dioxide and products showing ketene absorption at 2140 cm-1.The formation of pentatetraenone has not been established with certainty.The 3'-phenylsulfonylmethyl, phenylselenyl and methyl derivatives of (6a) are also described.
