Chiral oxazolines: A synthetic method to prepare optically active oxazolines through a copper‐catalyzed asymmetric desymmetrization of 1,3‐diols has been successfully developed. This reaction system tolerated a diverse range of substrates to give the desired oxazoline derivatives in good to excellent yields with high enantioselectivities (see scheme).
A copper‐catalyzed enantioselective transformation of tris(hydroxymethyl)aminomethane‐derived aminotriols was developed to provide multisubstituted oxazolines with a tetrasubstituted carbon center. The present transformation consisted of sequential reactions involving mono‐sulfonylation of aminotriols, subsequent intramolecular cyclization to afford prochiral oxazoline diols, and sulfonylative asymmetric desymmetrization of resultant oxazoline diols. In addition, the kinetic resolution process would be involved in the sulfonylative asymmetric desymmetrization step, which would amplify the enantiopurities of the desired products. Various aminotriols were tolerated in the present reaction, affording the desired oxazolines in good to high yields with excellent enantioselectivities. The synthetic utility of the present reaction was demonstrated by the transformation of the optically active oxazoline into a chiral α‐tertiary amine motif.
Desymmetrization of 1,3-Diols. -The procedure is applicable to various amino--1,3-diols tolerating (hetero)aryl substituents bearing electron-donating as well as electron-withdrawing groups, and moieties. The products are mostly obtained with high enantioselectivities. -(TSUDA, Y.; KURIYAMA, M.; ONOMURA*, O.; Chem. Eur. J. 18 (2012) 9, 2481-2483, http://dx.doi.org/10.1002/chem.201103800 ; Grad. Sch. Biomed. Sci., Nagasaki Univ., Nagasaki 852, Japan; Eng.) -S. Adam 29-129
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