(Z)-tert-Butyl 2-(4-amino-9H-fluoren-9-yl-idene)acetate.

The title compound, C(19)H(19)NO(2), obtained as an almost equimolar mixture (as shown by (1)H NMR) with the E isomer through a Wittig reaction between 4-amino-9H-fluoren-9-one and the stabilized ylide Ph(3)P=CHCO(2)C(CH(3))(3), was obtained pure in the Z configuration following crystallization from toluene. The mol-ecule 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 mol-ecules are linked by N-H⋯O hydrogen bonds, forming cyclic structures with R(4) (4)(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 inter-actions between the fluorene units [centroid-centroid distance = 3.583 (2) Å].