Stereochemistry and mechanistic study of intramolecular Pd(II)-catalyzed oxypalladation and 1,3-chirality-transfer reactions.
Pd(II)-catalyzed cyclizations of chiral epsilon-, zeta-, and eta-hydroxy-alpha,beta-unsaturated alcohols are described. The reactions took place stereospecifically to give chiral 2,5-disubstituted tetrahydrofurans, 2,6-disubstituted tetrahydropyrans, and 2,7-disubstituted oxepanes, respectively. The chirality of the carbon center of the chiral allylic alcohol is transferred stereospecifically to the carbon center of the newly generated oxacyclic ring. A plausible reaction mechanism involves 1) chiral-allylic-alcohol-induced syn facioselective formation of a Pd pi-complex, 2) syn oxypalladation, and 3) syn elimination of PdCl(OH), which provide a rational account for the stereochemical results.
Uenishi
Jun'ichi
J
Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto 607-8412, Japan. juenishi@mb.kyoto-phu.ac.jp
Vikhe
Yogesh Shankar
YS
Kawai
Nobuyuki
N
D000438:Alcohols / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism
D000438:Alcohols; D010165:Palladium; D010100:Oxygen