期刊
JOURNAL OF ORGANOMETALLIC CHEMISTRY
卷 603, 期 1, 页码 6-12出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/S0022-328X(00)00024-3
关键词
1,3-dipolar; lanthanide catalysis; isoxazolidine; 3,3 '-bis(2-oxazolyl)-1,1 '-bi-2-naphthols
New BINOL-derived ligands, 3,3'-bis(2-oxazolyl)-1,1'-bi-2-naphthols (BINOL-Box), bearing chiral bis-oxazoline at the 3,3'-carbons, were synthesized from commercially available 1,1'-bi-2-naphthol (BINOL). With the new ligands obtained, we found that asymmetric 1,3-dipolar cycloaddition reaction of N-benzylidenebenzylamine N-oxide (2) to 3-((E)-2-butenoyl)-1,3-oxazolidin-2-one (1) was catalyzed by BINOL-Box-scandium complexes to give isoxazolidine 3 in high yield with high diastereo- and enantioselectivity. For example, the reaction of 1 with 2 catalyzed by a 6 mol% (S,R)-7d and 5 mol% Sc(OTf)(3) complex proceeded to give the endo-3 as the major diastereomer with an endo:exo ratio of 97:3 and 87% ee of the endo-product in the presence of 4 Angstrom molecular sieves. Interestingly, the absolute configuration of the major product was changed according to the kind of additive used. (C) 2000 Elsevier Science S.A. All rights reserved.
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