N-Salicylideneanilines are interesting model compounds for understanding solid-state photochromism. The introduction of bulky substituents (trityl or tert-butyl groups) by chemical modification of the N-salicylideneaniline derivative is an effective method to build up photochromic solids. Alternatively, we propose, herein, a supramolecular approach to design photochromic materials which involves the introduction of a bulky anion in the structure. In this context, this is the first report on N-salicylideneamino-1-alkylpyridinium salts (iodide and tetraphenylboride salts). Iodide salts were obtained by alkylation of the parent N-salicylideneaminopyridine with the appropriate iodoalkane (iodomethane or iodoethane) in acetone. The iodide salts were used as the starting material for the production of tetraphenylborate salts by anion-exchange in methanol. All solids were characterized by means of X-ray diffraction and absorption spectroscopy. The effect of different counterions as well as the effect of the crystal structure on the solid-state photochromism is investigated.

A simple and efficient procedure for the Pd-catalyzed amination of N-free 2-chloro-7-azaindole is described, using either primary or secondary amines. An optimized combination of Brettphos, a Brettphos precatalyst, and LiHMDS in THF led us to a novel methodology, applied to various functionalized amines to study the scope of the reaction. This is the first report of cross-coupling amination on N-free 2-chloro-7-azaindole.

Hetero‐Michael addition on a chiral β′‐amino α,β‐unsaturated ketone gave, after some structural modifications, β,β′‐diamino ketals. Mannich‐type reactions of these diamines with an aldehyde led, with high diastereoselectivity, to trisubstituted piperidines. Another highly stereoselective Mannich cyclization, with an N‐acyliminium ion generated in situ from the corresponding imide, allowed the preparation of original polycyclic bispidine derivatives. The antinociceptive effect of the three compounds prepared was evaluated in vivo by using the writhing test. If the biological results for the analgesic properties were disappointing, compared with the bispidine HZ2, which has a high affinity for opioid receptors, the modularity of the approach offered the possibility of introducing many substituents for new applications, which was promising because the bispidine core has been described to have many different activities.

Scope and limitations in the diastereoselective preparation of 2,6-cis or 2,6-trans disubstituted piperidines are described, through intramolecular reaction of chiral β'-carbamate-α,β-unsaturated ketone. This methodology has been applied to the total synthesis of a few well chosen examples, such as (-)-solenopsine A and alkaloid (+)-241D.