Y. Uozumi et al., HOMOCHIRAL 2,2'-BIS(OXAZOLYL)-1,1'-BINAPHTHYLS AS LIGANDS FOR COPPER(I)-CATALYZED ASYMMETRIC CYCLOPROPANATION, Tetrahedron : asymmetry, 7(6), 1996, pp. 1603-1606
Homochiral 2,2'-bis[4-(alkyl)oxazol-2-yl]-1,1'-binaphthyls, which poss
ess both binaphthyl axial chirality and carbon centred chirality, were
prepared from 1,1'-binaphthyl-2,2'-dicarboxylic acid and 2-alkyl-2-am
inoethanols in high yields. Asymmetric cyclopropanation of styrene wit
h diazoacetates in the presence of 2 mol % of copper(I) triflate and 2
'-bis[(S)-4-(t-butyl)oxazol-2-yl]-1,1'-binaphthyl gave optically activ
e 2-(phenyl)cyclopropane-carboxylates of up to 97% ee. (C) 1996 Elsevi
er Science Ltd