Stereochemistry of Intermolecular Oxypalladation: Pd~(II)-Catalyzed1,3-Chirality Transfer Reaction of Chiral Allylic Alcohol with Methanol

摘要

The intermolecular oxypalladation of chiral nonracemic allylic alcohols (5)4, (R)-1, and (R)-3 inmethanol gave chiral nonracemic methyl allyl ethers (S)-2 and/or (R)-2 with excellent selectivity. Thereaction induced the 1,3-chirality transfer to give syn-S_N2' product exclusively throughsynoxypalladation. On the other hand, the anti-S_N2'product was produced in 20-33% THF,toluene, and CH_2Cl_2and predominantly in CH_3CN. The π-olefin-Pd complexesIandIIareproposed as important intermediates to explain the syn- and anti-oxypalladation pathways. Thebyproduct 9 was formed through the second syn-oxypalladation from the methyl allyl ether 2, thoughthe rate of this second reaction was far slower than that of allylic alcohol.