Optically active amines. 26. Spectral observations on chiral Schiff bases

Abstract

Smith et al.o i l was chromatographed o n silica gel w i t h benzene t o give 18 (40 mg, 40%) a n d 19 (31 mg, 33%).

A chiral Mn(IV) complex and its supramolecular assembly: Synthesis, characterization and properties

“…Cotton effects of negative sign are observed for these bands in the corresponding circular dichroism spectra which can be correlated with the absolute configuration of the amino alcohol moiety used. 12 Electronic and circular dichroism spectra of the complex 1 show red shift in the band position compared to the bands of the free ligand H 2 L (figure 3). In the visible region, an octahedral Mn(IV) d 3 system is expected to exhibit two electronic absorption bands due to d-d transitions viz.…”

The salicylidenamino chirality rule: a method for the establishment of the absolute configurations of chiral primary amines by circular dichroism

“…u'28>35 In methanol, the 397-nm CE, not observed when isooctane is the solvent, is due to the quinoid form (10) and that at 275 nm, persisting in isooctane, is due to the n -*• t* transition of the azomethine group. 54 Changes in the effective bulk size of the alkyl group, R group in 14a-c, have only a minimal effect on the conformational equilibrium of an IV-salicylidene derivative of a chiral a-phenylalkylamine, and conformer 14a makes the most important contribution to the CD spectrum. Thus, the IV-salicylidene derivatives of (S)-13b-d and CR)-13e display CD spectra very similar to that of the iV-salicylidene derivative of (S)-13a with positive CEs for bands I and II.11,28,41 '56 The absolute configurations of (S)-13b,c were originally assigned on the basis of the ORD of their iV-salicylidene derivatives.10 These assignments were each confirmed by subsequent chemical degradation.57,58 2 (S)-15 For (S)-l-aminoindan [(S)-15], the observed13 positive CEs are also predicted by a similar analysis.…”