- Chemistry via metal atom cocondensation: Isomerization and complexation reactions of organocyclopropanes and spirocycles
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Reactions of metal atoms with structurally diverse organocyclopropanes have been studied. Quadricyclane (4) is isomerized to norbornadiene (5) upon cocondensation with a variety of metals, but control experiments suggest this reaction is heterogeneously catalyzed by metal aggregates which form upon warming the matrix. Norcarane (6), 2-norcarene (7), 3-carene (8), and 3-norcarene (9) give no reaction when cocondensed with a broad spectrum of metal atoms, despite the presence of an olefinic group in the latter three. When cyclopropylbenzene (11) is cocondensed with chromium, only bis(cyclopropylbenzene)chromium(0) (12) is formed. However, reaction of iron atoms with spiro[2.4]hepta-4,6-diene (14) yields a 14:64:6:17 ratio of 1,1′-diethylferrocene (15), 1-ethyl-1′-vinylferrocene (16), 1,1′-divinylferrocene (17), and [4]ferrocenophane (18) in 44% yield based upon iron. Cocondensations of iron with spiro[2.4]heptane (20; no reaction) and spiro[4.4]nona-1,3-diene (23; formation of bis(tetrahydroindenyl)iron (24) and 1,2-tetramethylene-1′-butylferrocene (25)) are also reported. Possible mechanisms of spirocycle (14, 23) ring opening and product formation are discussed. No volatile bis(arene)chromium(0) complexes are formed when benzocyclopropene (27) and dispiro[2.2.2.2]deca-4,9-diene (28) are cocondensed with chromium, although the former is polymerized. The preparation of 18 from 1,1′-dilithioferrocene (19) and 1,4-dibromobutane is also described.
- Lee Hanlan,Ugolick,Fulcher,Togashi,Bocarsly,Gladysz
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p. 1543 - 1551
(2008/10/08)
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