A new strategy has been established for the kineticresolution of racemic allylic alcohols through a palladium/sulfonyl‐hydrazide‐catalyzed asymmetric OH‐substitution under mild conditions. In the presence of 1 mol % [Pd(allyl)Cl]2, 4 mol % (S)‐SegPhos, and 10 mol % 2,5‐dichlorobenzenesulfonyl hydrazide, a range of racemic allylic alcohols were smoothly resolved with selectivity factors of more than
Triphenylphosphine-mediated olefination of aldehydes with (Z)-(2-acetoxyalk-1-enyl)phenyl-λ3-iodanes: generation and reaction of (2-oxoalkyl)phenyl-λ3-iodanes
(Z)-(2-Acetoxyalk-1-enyl)phenyl-λ3 -iodanes, on treatment with triethylamine in methanol in the presence of triphenylphosphine, undergo Wittig olefination with aldehydes, which involves the intermediacy of α-iodanyl ketones generated by in situ protonation of monocarbonyliodoniumylides.
Highly enantioselective synthesis of 1,3-mercapto alcohols from α,β-unsaturated ketones: asymmetric bifunctional group exchange reaction
作者:Hiroaki Shiraki、Kiyoharu Nishide、Manabu Node
DOI:10.1016/s0040-4039(00)00395-6
日期:2000.4
3-mercapto alcohols were synthesized from α,β-unsaturatedketones using a chiral reagent B and dimethylaluminum chloride in two steps. The transformation involved a tandemMichael addition–MPV reduction and a base-catalyzed elimination. The two newly created chiral carbons in trans-chalcone derivatives were enantioselectively controlled to a high degree. Using the above transformation, an asymmetric bifunctional
A carbonylative Mizoroki–Heck reaction using alkyl iodides was achieved with a Pd/photoirradiation system using DBU as a base. In this reaction, alkyl radicals were formed from alkyl iodides via single-electrontransfer (SET) and then underwent a sequential addition to CO and alkenes to give β-keto radicals. It is proposed that DBU would abstract a proton α to carbonyl to form radical anions, giving
Palladium-catalyzed coupling reaction of acylzirconocene chlorides with hypervalent iodonium salts: synthesis of aryl-substituted ketones
作者:Suk-Ku Kang、Seok-Keun Yoon
DOI:10.1039/b110983a
日期:2002.2.6
The palladium-catalyzed acylation reaction of alkenoyl- and alkanoylzirconocene chlorides with hypervalent iodonium salts afforded the acylated aromatic compounds under mild conditions.