Asymmetric epoxidation of (Z)-enol esters catalyzed by titanium(salalen) complex with aqueous hydrogen peroxide

作者：Matsumoto Kazuhiro; Feng Chao; Handa Satoshi; Oguma Takuya; Katsuki Tsutomu^*

来源：Tetrahedron, 2011, 67(35): 6474-6478.

DOI：10.1016/j.tet.2011.06.022

• Asymmetric reaction
• Epoxidation
• Hydrogen peroxide
• Titanium
• Enol ester

Titanium(salalen) complex 1 was an effective catalyst for asymmetric epoxidation of enol esters. Although (E)-enol esters were reluctant to proceed, (Z)-enol esters underwent asymmetric epoxidation to give the epoxides in high yields with high enantioselectivity ranging from 86 to >99% ee in the presence of aqueous hydrogen peroxide as the stoichiometric oxidant. Complete enantioselectivity was observed in the reaction of (Z)-3,3-dimethylbut-1-en-1-yl 4-methoxybenzoate. The obtained epoxide was readily transformed into the corresponding 1,2-diol by reduction with lithium borohydride without erosion of the high enantiomeric excess.

• 出版日期2011-9-2