200408-69-1Relevant academic research and scientific papers
Asymmetric Michael addition reactions of 2-silyloxyfurans catalyzed by binaphthyldiimine-Ni(II) complexes
Suga, Hiroyuki,Kitamura, Takeo,Kakehi, Akikazu,Baba, Toshihide
, p. 1414 - 1415 (2004)
N,N′-Bis(2-quinolylmethylene)-1,1′-binaphthyl-2, 2′-diamine-Ni(II) complex and analogous complexes were found to be efficient chiral Lewis acid catalysts for the asymmetric Michael addition reactions between 2-silyloxyfurans and 3-alkenoyl-2-oxazolidinones, for which asymmetric inductions of up to 97% ee were obtained.
A new pyridine-2,6-bis(oxazoline) for efficient and flexible lanthanide-based catalysts of enantioselective reactions with 3-alkenoyl-2-oxazolidinones
Desimoni, Giovanni,Faita, Giuseppe,Guala, Matilde,Laurenti, Anna,Mella, Mariella
, p. 3816 - 3824 (2007/10/03)
A new pyridine-2,6-bis(oxazoline) (4) has been easily synthesised from the reaction of (1S,2S)-2-amino-1-phenylpropane-1,3-diol (1) and dimethyl pyridine-2,6-dicarboximidate (2), followed by TIPS (TIPS = triisopropylsilyl) protection of the 4′-CH2OH group. The catalysts derived from 4 and eight lanthanide(III) triflates have been tested over three reactions involving 3-acryloyl- and 3-crotonoyloxazolidinones (5a,b): the Diels-Alder (DA) reaction with cyclopentadiene, the 1,3-dipolar cycloaddition with diphenyl nitrone and the Mukaiyama-Michael reaction with 2-trimethylsilyloxyfuran. Several reactions exhibit very good enantioselectivity (ee > 90%), and the opposite enantiomers can be easily obtained simply by changing the cation. This specific feature of the ligand can be appreciated in the DA reaction of 5a, since the catalyst [ScIII(4)] gives the adduct (2′S)-9a with 99% ee, whereas the catalyst [YIII(4)] gives the opposite enantiomer with 95% ee. A rationale of the enantioselectivity is proposed on the basis of the NMR spectra of La-based complexes involving 4 and 5 as ligands.
A new methodology for the stereoselective synthesis of 4-substituted butenolides: Asymmetric Michael addition reaction of 2-(trimethylsilyloxy)furans to oxazolidinone enoates
Kitajima, Hiroshi,Ito, Katsuji,Katsuki, Tsutomu
, p. 17015 - 17028 (2007/10/03)
Chiral Lewis acid promoted Michael addition of 2-(trimethylsilyloxy)furans to oxazolidinone enoates (2) in the presence of hexafluoroisopropanol proceeded stereoselectively to give 4-substituted butenolides in good yields. A 1:1 complex prepared in situ from Sc(OTf)3 and 3,3'-bis(diethylaminomethyl)-1,1'-bi-2-naphthol 5b showed excellent anti-selectivity and moderate enantioselectivity, while Cu(OTf)2-bis(oxazoline) complex exhibited excellent enantioselectivity and moderate to good anti-selectivity.
