Synthesis of chiral bis-oxazines: a preliminary assessment of helical conformational framework

Synthesis of enantiomerically pure helicene-like mono 1,3-oxazines from 1,1′-binaphthyl-2,2′,7-triol and study of their chiroptical properties

Several helicene-like molecules have been synthesized and characterized. The effect of helicene-like structural arrangement was more prominent in the chiroptical properties as compared to the stereogenic center of the diastereomeric compounds.

Synthesis of enantiomerically pure helicene like bis-oxazines from atropisomeric 7,7'-dihydroxy BINOL: Preliminary measurements of the circularly polarized luminescence

Racemic sample of 2,2',7,7'-tetrahydroxy-1,1'-binaphthyl was resolved with (S)-proline and the separated enantiomers were independently converted to atropisomeric bis-oxazines by aromatic Mannich reaction. These chirally pure oxazines were then converted to the helicene like cyclic ethers. The Circularly Polarized Luminescence (CPL) profile was consistent with the isolation of the targeted helical-like molecules in optically pure form, prepared from the achiral primary amines. The compounds of interest displayed active and opposite CPL activities for each sets of the helicene like isomers (P)-/(M)-3 and (P)-/(M)-5.