Norbomane fused

Finally, it is important to mention that there are other related publications in which porphyrin macrocycles are not directly used as dipolarophiles but are transformed into new derivatives that can react with carbonyl ylides via ACE (alkene cyclobutene epoxide) reactions. This idea arose in 1997, when Russell and co-workers found that fused ester-activated cyclobutene epoxides 86 can be ring-opened to give carbonyl ylides 87, and that these can be trapped stereospecifically by ring-strained alicyclic dipolarophiles, such as 2,5-norbomadiene, to form hetero-bridged norbomanes 88 in good yields, through ACE transformations (Scheme 31) <97CC1023>. 

The aziridine-coupling reaction had the ability to introduce bridge-substituents X or Y on either side of the iV-bridge in fused 7-azanorbomanes 87 and allowed a rare opportunity to study through-space effects on A-bridge hybridisation and JV-alkyl invertomerisation in fused 7-aza norbomanes. 

A multipurpose template is the oxazolidinone 19 which is endo-fused to a norbomane skeleton. Proper A-acyl derivatives are useful for asymmetric alkylation, conjugate addition, and Diels-Alder reactions. 

More recently, chiral Ru-porphyrin polymers were used for catalytic asymmetric carbene transfer. A C2-symmetric group containing two norbomane moieties fused to the central vinyl substituted benzene ring of a porphyrin was chosen in order to induce the chirality. Then the chiral ruthenium vinylporphyrin 101 was involved into radical copolymerization with styrene and DVB or EGDMA to lead respectively to monolithic resins chiral 102 and 103 which were crushed (Scheme 48). 

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