(Z)-tert-Butyl 2-(4-amino-9H-fluoren-9-ylidene)acetate

Abstract

The title compound, C19H19NO2, obtained as an almost equimolar mixture (as shown by 1H NMR) with the E isomer through a Wittig reaction between 4-amino-9H-fluoren-9-one and the stabilized ylide Ph3P=CHCO2C(CH3)3, was obtained pure in the Z configuration following crystallization from toluene. The molecule shows a planar arrangement of the ring system and the new double bond, whereas the carbonyl O atom forms a 45.1 (3)° dihedral angle with it. The molecules are linked by N—H...O hydrogen bonds, forming cyclic structures with R44(24) graph-set motifs. These motifs are connected to each other, giving rise to a sheet structure parallel to the ab plane. The linkage within the sheets is further enhanced by π–π stacking interactions between the fluorene units [centroid–centroid distance = 3.583 (2) Å].