Rhodium-catalyzed [(3+2)+2] carbocyclization of alkynylidenecyclopropanes with substituted allenes: stereoselective construction of tri- and tetrasubstituted exocyclic olefins.
The development of the stereoselective rhodium-catalyzed [(3+2)+2] carbocyclization of alkynylidenecyclopropanes (ACPs) with substituted allenes is described. This work demonstrates that activated and unactivated allenes preferentially undergo carbometalation at the distal terminus to generate tri- and tetrasubstituted exocyclic olefins with a neutral rhodium catalyst. In addition, this method provides a strategy for the total synthesis of the guaiane family of sesquiterpenes, which are not directly accessible using alkynes as exogenous π-components. Finally, the preparation of the bicyclo[5.4.0]undecane ring system using a homologated ACP tether serves to further illustrate the versatility of this approach.
Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, K7L 3N6, Ontario (Canada). Andrew.Evans@chem.queensu.ca.
P Andrew
PA
Evans
Daniela E
DE
Negru
Deju
D
Shang
D000475:Alkenes / Q000138:chemical synthesis / Q000737:chemistry*; D001643:Bridged Bicyclo Compounds / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D003521:Cyclopropanes / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
D000475:Alkenes; D001643:Bridged Bicyclo Compounds; D003521:Cyclopropanes; C030797:cyclopropane; D012238:Rhodium
allenes; cyclizations; olefins; rhodium; synthetic methods