Transition metal-catalyzed [4 + 2 + 2] cycloadditions of bicyclo[2.2.1]hepta-2,5-dienes (norbornadienes) and bicyclo[2.2.2]octa-2,5-dienes.
The transition-metal-catalyzed [4 + 2 + 2] cycloadditions of norbornadienes, bicyclo[2.2.2]octa-2,5-diene, and benzobarrelene with 1,3-butadienes proceed in excellent yields using cobalt-based catalytic systems. Two key distinctions between these [4 + 2 + 2] cycloadditions and the corresponding transition-metal-catalyzed [2 + 2 +2] reactions of norbornadiene are the requirement of a bimetal catalytic system with a bisphosphine ligand for the former and exclusive regioselectivity in the [4 + 2 + 2] reaction of 2-substituted norbornadienes to produce 1-substituted adducts. These distinctions may indicate two distinct mechanisms for the [4 + 2 + 2] and [2 + 2 + 2] reactions.
Chen
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Y
Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
Kiattansakul
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R
Ma
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Snyder
J K
JK
D001952:Bridged-Ring Compounds / Q000737:chemistry; D002384:Catalysis; D006844:Hydrocarbons, Cyclic / Q000737:chemistry; D019216:Metals, Heavy; D009636:Norbornanes / Q000737:chemistry*
D001952:Bridged-Ring Compounds; D006844:Hydrocarbons, Cyclic; D019216:Metals, Heavy; D009636:Norbornanes