Synthesis, resolution and crystal structures of two enanti­omeric rhodamine derivatives

The title mol­ecule, rac-6′-bromo-3′-di­ethyl­amino-3H-spiro­[2-benzo­furan-1,9′-xanthen]-3-one, C(24)H(20)BrNO(3), was synthesized and the two enanti­omers which formed were separated. The structures of all three compounds were determined and compared with those of a variety of related derivatives. A notable feature is the fold of the xanthene portion which ranges from 15.15 (13)° in the racemate to 2.42 (2)° in one mol­ecule of the R enanti­omer with that for the S enanti­omer having an inter­mediate value. The differences are attributed to the number and severity of inter­molecular inter­actions which include C—H⋯O hydrogen bonds, C—H⋯π(ring) and, in the S enanti­omer, a π-stacking inter­action between the carbonyl group and an aromatic ring.