A meta-Xylylene by Bamford-Stevens-Reaction of a Fulvene-Ketene-Adduct

Article abstract of DOI:10.1002/hlca.19840670525

Heating the sodium salt 8 of the tosylhydrazone 4 of 4-isopropyliden-7,7-dimethylbicyclo<3.2.0>hept-2-en-6-one (3; obtained by the addition of dimethylketene to 6,6-dimethylfulvene (1)), in diglyme at 130 deg C led to the octamethyl-<2.2>metacyclophane 10 (17 percent).The latter probably was formed by dimerization of the non-Kekule molecule m-xylylene 14, which, in turn, could have arisen via the homofulvene 13 from the carbene 12.A second product in the thermolysis of 8 was the tricycle 9 (9 percent), as a result of an intramolecular insertion of the carbene C-atom in 12 into a methyl C,H-bond.Further products were the azines 11a, 11b (50 percent), of the type known as byproducts in Bamford-Stevens reactions.Heating dry 8 afforded 9 (9 percent) and the two benzene derivatives 15 (9 percent) and 16 (3 percent).The tosylhydrazone 4 could be recovered by reaction of 11a, 11b with p-toluenesulfonohydrazide.