In the crystal structure of 2, two crystallographically independent molecules are present in the asymmetric unit. During the refinement, the CO i Pr group of one molecule was found to be disordered over two orientations (named A and B) with the site occupancy factors refined as 0.725(5) and 0.275 (5), respectively. Restraints were applied in SHELXL to the bond distances and angles in the disordered parts using the DANG, DFIX and SADI instructions, and to the displacement parameters of the disordered atoms using the SIMU instruction. The H-atoms on the N-atoms were located in a difference Fourier map, and were freely refined with Uiso(H) = 1.2Ueq(N). All remaining H-atoms were placed geometrically and refined isotropically using a riding model, with C-H = 0.95 Å (Caromatic), 0.98 Å (C-methyl), 0.99 Å (C-methylene) and 1.00 Å (C-methine), in association with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(C-methyl).