Ck. Ghosh et S. Sahana, BENZOPYRANS .31. REACTION OF YL-2-(6-METHYL-4-OXO-4H-I-BENZOPYRAN-3-YL)ETHYLENE WITH PHENYLDIAZOMETHANE, Tetrahedron, 49(19), 1993, pp. 4135-4140
Phenyldiazomethane yields with the title alkene 1 a mixture of the tra
ns-cyclopropane 6. benzopyran 8, pyrazole 9, and cis-dihydrofuran 12.
The cyclopropane 6 thermally rearranges to a trans-dihydrofuran tentat
ively assigned the structure 4.