Palladium-catalyzed diastereo- and enantioselective Wagner-Meerwein shift: control of absolute stereochemistry in the C-C bond migration event.
Inducing absolute stereochemistry in Wagner-Meerwein shifts was examined in a ring expansion protocol. Initiated by generation of a pi-allylpalladium intermediate by hydropalladation of allenes, the ring expansion of allenylcyclobutanol substrates proceeded with excellent diastereo- and enantioselectivities. The results demonstrate that, during the C-C bond migration process, our chiral catalysts can control the stereochemistry of both the pi-allylpalladium intermediate and the corresponding migration bond. Moreover, the stereochemical outcome of the reaction can be rationalized very well with the working model of the chiral catalyst. The method provides an efficient way to synthesize highly substituted cyclopentanones with an alpha-chiral O-tertiary center which has various synthetic applications.
Trost
Barry M
BM
Department of Chemistry, Stanford University, Stanford, California 94305, USA. bmtrost@stanford.edu
Xie
Jia
J
D000438:Alcohols / Q000138:chemical synthesis / Q000737:chemistry*; D000466:Alkadienes / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003503:Cyclobutanes / Q000138:chemical synthesis / Q000737:chemistry*; D003517:Cyclopentanes / Q000138:chemical synthesis*; D018020:Lithium Compounds / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism
D000438:Alcohols; D000466:Alkadienes; D000498:Allyl Compounds; D003503:Cyclobutanes; D003517:Cyclopentanes; D018020:Lithium Compounds; C007201:cyclopentanone; C025947:propadiene; D010165:Palladium