On the stereochemical course of palladium-catalyzed cross-coupling of allylic silanolate salts with aromatic bromides.
The stereochemical course of palladium-catalyzed cross-coupling reactions of an enantioenriched, alpha-substituted, allylic silanolate salt with aromatic bromides has been investigated. The allylic silanolate salt was prepared in high geometrical (Z/E, 94:6) and high enantiomeric (94:6 er) purity by a copper-catalyzed S(N)2' reaction of a resolved allylic carbamate. Eight different aromatic bromides underwent cross-coupling with excellent constitutional site-selectivity and excellent stereospecificity. Stereochemical correlation established that the transmetalation event proceeds through a syn S(E)' mechanism which is interpreted in terms of an intramolecular delivery of the arylpalladium electrophile through a key intermediate that contains a discrete Si-O-Pd linkage.
Denmark
Scott E
SE
Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA. sdenmark@illinois.edu
Werner
Nathan S
NS
D000498:Allyl Compounds / Q000737:chemistry*; D001555:Benzene Derivatives / Q000138:chemical synthesis*; D001969:Bromobenzenes / Q000737:chemistry*; D002384:Catalysis; D010165:Palladium / Q000737:chemistry; D012821:Silanes / Q000737:chemistry*; D013237:Stereoisomerism
D000498:Allyl Compounds; D001555:Benzene Derivatives; D001969:Bromobenzenes; D012821:Silanes; D010165:Palladium