Asymmetric Synthesis by the Intramolecular Haloetherification Reaction of Ene Acetal: Discrimination of Prochiral Dienes in Cyclohexane Systems
作者:Hiromichi Fujioka、Naoyuki Kotoku、Yoshinari Sawama、Hidetoshi Kitagawa、Yusuke Ohba、Tsung-Lung Wang、Yasushi Nagatomi、Yasuyuki Kita
DOI:10.1248/cpb.53.952
日期:——
A novel asymmetricsynthesis of the cyclohexane derivative functionalized by some substituents has been developed from the diene acetals (1), prepared from the corresponding diene aldehyde and (+)-hydrobenzoin. The treatment of 1 with NBS in the presence of MeOCH2CH2OH predominantly afforded 2 in a stereoselective manner. Subsequent alkylation of the methoxyethoxy group produced the optically active
Chiral enolates for highly stereoselective aldol reactions—Scope and limitations
作者:Matthias Welker、Simon Woodward
DOI:10.1016/j.tet.2010.10.048
日期:2010.12
of α,β-disubstituted ketonesthrough aldol reactions are compared. A one-pot ACA/aldol domino process is lower yielding than alternative procedures involving enantiomerically pure β-substituted silyl enol ethers. The use of chiral acetals derived from hydrobenzoin provides access to syn and anti diols in moderate to good yields and high diastereoselectivities. A novel synthesis of functionalized β,γ-unsaturated