Seven-Membered Rings from Fragmentation Strategies

SEVEN-MEMBERED RINGS FROM FRAGMENTATION STRATEGIES 

Winkler employed a photochemical approach to the in-out tricyclic core of ingenol, beautifiilly illustrating the utility of a fragmentation strategy in complex molecule synthesis (Eq. 33).  

Fragmentations of bicyclo[3.2.0]heptanes are commonly used to prepare seven-membered rings. The value of this process arises from 

Marples reported radical-induced fragmentation of a cyclohexene oxide derivative to form a heterocyclic seven-membered ring (Eq. 36).  

Paquette used a fragmentation strategy to elaborate the ring system of 18-oxo-3-virgene. Upon treatment with triethylamine in warm methanol, the starting material fragments to the seven-membered ring (Eq. 37). 

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IV. SEVEN-MEMBERED RINGS FROM FRAGMENTATION STRATEGIES... 

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