Stereoselective pinacol coupling of chiral formylferrocene using divalent samarium triflate: preparation of a new chiral bisferrocenyl oxazoline ligand and its application to asymmetric Diels-Alder reactions.
[reaction: see text] The pinacol coupling reaction of planar chiral ortho-oxazoline-substituted formylferrocene was smoothly mediated by SmI2 or Sm(OTf)3 to give the (R,R) isomer selectivity (up to 76% diastereomeric excess). The combination of Yb(OTf)3 and the (R,R)-ferrocenyl diol was revealed to be a good catalyst for the asymmetric Diels-Alder reaction of 3-acyloxazolidinone with cyclopentadiene, and the endo adduct was produced in up to 80% enantiomeric excess.
Fukuzawa
Shin-ichi
S
Department of Applied Chemistry, Institute of Science and Engineering, Chuo University, Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan. fukuzawa@chem.chuo-u.ac.jp
Yahara
Yuusuke
Y
Kamiyama
Akira
A
Hara
Masumi
M
Kikuchi
Satoshi
S