Crystal structure of tert-butyl 4-[4-(4-fluoro-phen-yl)-2-methyl-but-3-yn-2-yl]piperazine-1-carboxyl-ate.

The title sterically congested piperazine derivative, C(20)H(27)FN(2)O(2), was prepared using a modified Bruylants approach. A search of the Cambridge Structural Database identified 51 compounds possessing an N-tert-butyl piperazine substructure. Of these only 14 were asymmetrically substituted on the piperazine ring and none with a synthetically useful second nitro-gen. Given the novel chemistry generating a pharmacologically useful core, determination of the crystal structure for this compound was necessary. The piperazine ring is present in a chair conformation with di-equatorial substitution. Of the two N atoms, one is sp (3) hybridized while the other is sp (2) hybridized. Inter-molecular inter-actions resulting from the crystal packing patterns were investigated using Hirshfeld surface analysis and fingerprint analysis. Directional weak hydrogen-bond-like inter-actions (C-H⋯O) and C-H⋯π inter-actions with the dispersion inter-actions as the major source of attraction are present in the crystal packing.