Regio- and enantioselective intermolecular rhodium-catalyzed [2+2+2] carbocyclization reactions of 1,6-enynes with methyl arylpropiolates.
Transition metal-catalyzed [m+n+o] carbocyclization reactions provide powerful methods for the construction of complex polycyclic systems that are generally not accessible through classical pericyclic reactions. We have developed the first regio- and enantioselective crossed intermolecular rhodium-catalyzed [2+2+2] carbocyclization of carbon- and heteroatom-tethered 1,6-enynes with unsymmetrical 1,2-disubstituted alkynes. This study clearly delineates the ligand requirements for obtaining excellent regio- and enantioselectivity. Furthermore, the ability to utilize various electron-withdrawing groups, and to introduce quaternary carbon stereogenic centers, provides the level of versatility necessary for its application to target-directed synthesis. Additional studies on the development and application of this novel methodology to the total synthesis of natural products are currently underway.
Evans
P Andrew
PA
Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA. paevans@indiana.edu
Lai
Kwong Wah
KW
Sawyer
James R
JR
D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D006574:Heterocyclic Compounds, 2-Ring / Q000138:chemical synthesis*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
D000480:Alkynes; D006574:Heterocyclic Compounds, 2-Ring; D009942:Organometallic Compounds; D011422:Propionates; D012238:Rhodium