Reactions of Tricyclic Vinylcyclopropanes with Metal Carbonyls

Abstract

AbstractIrradiation of the tricyclic vinylcyclopropane 3 and Fe(CO)5 resulted in the formation of the s̀,π‐bonded iron complex 7 and the π,π‐bonded iron complex 8 (Scheme 2). Complex 8 was easily degraded with silica gel to give hydrocarbon 9, which reproduced 8 by photolysis in the presence of Fe(CO)5. Photolysis of 7 afforded a mixture of 3 (23%), 9 (27,5%), and three other hydrocarbons. Oxidative degradation of 7 with ceric ammonium nitrate in methanol gave the dimethoxy‐hydrocarbon 10. ‐ The tricyclic hydrocarbon 3 isomerized thermally to the bicyclic hydrocarbon 11 (with CH3C(9) in an exo position) via a homosigmatropic [1,5]‐H‐shift. On the other hand, 3 was converted into the other isomer 14 (with CH3C(9) in an endo position) by action of Mo(CO)6 or TsOH. Both isomers 11 and 14 reacted with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione to give the isomeric Diels‐Alder adducts 12 and 15, respectively, which were photochemically converted into the cage compounds 13 and 16, respectively (Scheme 3). ‐ Photochemical reaction of the tricyclic vinylcyclopropane 6 with Fe(CO)5 gave the σ,π‐bonded iron complexes 17 and 18. Heating of 17 at 80° resulted in a loss of one mol of carbon monoxide to give 18 in quantitative yield. Oxidative degradation of 17 with ceric ammonium nitrate in ethanol afforded the polycyclic lactones 19 and 20 by a novel type of reaction (Scheme 4). ‐ The tricyclic ketone 21 was thermally converted into the α,β‐unsaturated ketone 22 via a homosigmatropic [1,5]‐H‐shift. The configuration at C(7) of 22 was confirmed to be same as that of 11 (CH3C(9) in an exo position) by chemical conversions: 22 was reduced with NaBH4 to alcohol 23 which, in turn, was dehydrated with POCl3/pyridine to 11 (Scheme 5). Reaction of ketone 21 with Mo(CO)6 gave the α,β‐unsaturated ketone 25 and a cage compound X, whose structure was not fully elucidated. ‐ Reaction of the polycyclic epoxide 26 with Fe2(CO)9 or Mo(CO)6 yielded the allyl alcohol 27 in a novel type of reaction. The epoxides 29 and 32 were similarly converted into the corresponding allyl alcohols 30 and 33, respectively (Scheme 6).