posted on 2016-12-13, 16:10authored byNaoya Sagawa, Haruka Sato, Seijiro Hosokawa
Remote
asymmetric induction by the vinylogous Mukaiyama aldol reaction
using the acetate-type vinylketene silyl N,O-acetal possessing a chiral auxiliary has been achieved.
The silyl N,O-acetal derived from
crotonate and l-valine afforded the O-silylated
5R- and 5S-adducts selectively by
treatment with SnCl4 and BF3·OEt2, respectively. The SnCl4-mediated isomerization of silyl
dienol ether was found, and the resulting major isomer showed high
reactivity to give γ-adduct in high stereoselectivity.