Selective Transformations of Carbonyl Functions in the Presence of α,β-Unsaturated Ketones: Concise Asymmetric Total Synthesis of Decytospolides A and B
摘要:
Enones selectively react with a combination of PPh3 and TMSOTf to produce phosphonium silyl enol ethers, which work as protective groups of enones during the reduction of other carbonyl functions and can be easily deprotected to regenerate parent enones at workup. Furthermore, the first ketone selective alkylations in the presence of enones were also accomplished. This in situ protection method was applied to concise asymmetric total syntheses of decytospolides A and B.
Titanocene-Catalyzed Asymmetric Ketone Hydrosilylation: The Effect of Catalyst Activation Protocol and Additives on the Reaction Rate and Enantioselectivity
作者:Jaesook Yun、Stephen L. Buchwald
DOI:10.1021/ja990450v
日期:1999.6.1
The efficient asymmetric hydrosilylation of ketones with a chiral titanocene catalyst has been realized. In this procedure, (R,R)-ethylenebis(tetrahydroindenyl) titanium difluoride (1) was used as the precatalyst, and alcohol additives were employed. Aromatic and α,β-unsaturated ketones were reduced to the corresponding alcohols with a high level of enantioselectivity.