Enantioselective alkylation of aldehydes using functionalized alkylboron reagents catalyzed by a chiral titanium
Ravindra Kumar1, Hiroki Kawasaki, Toshiro Harada
1Venture Laboratory, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
Abstract:
A practical method is developed for the synthesis of enantioenriched functionalized secondary alcohols through catalytic enantioselective alkylation of aldehydes. Functionalized alkylboron reagents, [FG-(CH2)n]3B (FG = Br, TIPSO, PhtN, CO2(i)Pr, and CN) prepared from terminal olefin precursors by hydroboration, undergo enantioselective addition to aldehydes in the presence of a catalytic amount (5 mol %) of 3-(3,5-diphenylphenyl)-H8-BINOL and excess titanium tetraisopropoxide to afford the corresponding functionalized alcohols in high enantioselectivities up to 99% ee.
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