Ironcarbonyl Complexes of 5,6-Dimethylidene-7-oxabicyclohept-2-ene Derivatives. Synthesis of Substituted Tricarbonyl(ortho-quinodimethane)iron Complexes and 2-Indanones

Article abstract of DOI:10.1002/hlca.19870700715

The 1-dimethoxymethyl-5,6-dimethylidene-7-oxabicyclo<2.2.1>hept-2-ene (9) has been prepared.On treatment with Fe2(CO)9, the endocyclic double bond C(2)=C(3) was coordinated first giving the corresponding exo-Fe(CO)4 complex 10.The latter reacted with Fe2(CO)9 and afforded cis heptacarbonyl-μ-<1RS,2SR,3RS,4SR,5RS,6SR)-2,3-η-(1-(dimethyoxymethyl)-5,6-dimethylidene-7-oxabicyclo<2.2.1>hept-2-ene)>diiron (11) as a major product.On heating, 11 undervent deoxygenation of the 7-oxabicyclo<2.2.1>heptene moiety yielding tricarbonyliron (13).In MeOH, a concurrent, regioselective methoxycarbonylation was observed giving tricarbonyliron (14).Oxidative removal of the Fe(CO)3 moiety in 13 and 14 did not afford the expected ortho-quinodimethane derivatives but led to CO insertions giving 2,3-dihydro-2-oxo-1H-indene-4-carbaldehyde (2) and methyl 7-formyl-2,3-dihydro-2-oxo-1H-indene-5-carboxylate (21), respectively.