Intramolecular cyclopropanation-ring fragmentation leading to spirocyclic ring construction: a stereoselective synthesis of .beta.-chamigrene
摘要:
The transannular cyclopropanation of a keto carbene generated by Rh2(OAc)4 catalysis on a bicyclic dihydropyran nucleus provided a key oxatricyclic ketone intermediate for the synthesis of the [6.6] spirocyclic ring construction. Selective fragmentation of the cyclopropane followed by hydrolytic cleavage of the C-O bond provided the spirocyclic skeleton. Functional group manipulations to adjust oxidation states led to a total synthesis of (+/-)-beta-chamigrene in 14 steps without the use of protection/deprotection schemes.
Intramolecular cyclopropanation-ring fragmentation leading to spirocyclic ring construction: a stereoselective synthesis of .beta.-chamigrene
摘要:
The transannular cyclopropanation of a keto carbene generated by Rh2(OAc)4 catalysis on a bicyclic dihydropyran nucleus provided a key oxatricyclic ketone intermediate for the synthesis of the [6.6] spirocyclic ring construction. Selective fragmentation of the cyclopropane followed by hydrolytic cleavage of the C-O bond provided the spirocyclic skeleton. Functional group manipulations to adjust oxidation states led to a total synthesis of (+/-)-beta-chamigrene in 14 steps without the use of protection/deprotection schemes.