Intramolecular C-H insertion reactions of acetoxy Fischer carbene complexes

The reaction of 4-substituted 2-(t-butyldimethylsiloxy)-1,3-butadiene with acetoxy chromium Fischer carbene complexes afforded bicyclo[4.1.0]heptene derivative 3, 18, an intramolecular C-H insertion product of the initially formed Diels-Alder adduct 6. The role of the metal and the heteroatom ligand in the carbene complex, and of the substituent at 3-position in 6 on the C-H insertion has been examined.