Some reactions of gem-dibromocyclopropanes and metal carbonyls

[[abstract]]"A series of gem-dibromocyclopropanes were treated with various metal complexes. Among the metal complexes, Ru(CO)2(PPh3) 3, Ru(CO)3(PPh3) 2, and Mo(CO)6 were able to remove a bromine atom from 1,1-dibromo-2-phenylcyclopropanes (1) to yield a series of corresponding of 1-bromo-2-phenylcyclopropanes (2). Upon the treatment of 1 with Cr(CO)6 in DMSO, a series of allenes were obtained in good yields. The correlation between the rate of formation of allenes and the substituents on the benzene gives a negative coefficient which suggests the dibromocyclopropanes possesses as an electrophile toward to Cr(CO)6. In the presence of Cr(CO)6, gem-dibromobicyclo[n,1,0]alkanes (4) in DMF or DMSO solution underwent the cleavage of carbon-bromine bond followed by ring-expansion and coupling reaction to form bicycloalkenes 7