Transition metal catalyzed reactions on allenic substrates for heterocyclic synthesis.

The main subject of this thesis are transition metal catalyzed reactions onto allenic substrates. The reactivity of allenic double bonds in presence or absence of transition metal was investigated and studied in order to favor intramolecular processes able to yield nitrogen-containing heterocyclic structures. We investigated the feasibility of cyclization processes onto allenamides that could have been built starting from α-aminoacids, that is, with a pre-introduced chiral information in the starting materials able to be kept till the obtainment of the final enantiopure products. At first we developed a procedure for building monocyclic five- and six-membered nitrogen containing heterocycles from under basic conditions. Next, we studied the Pd-catalyzed nitrogen addition onto the -carbon of the aforementioned allenes in order to obtain imidazolidinones structures, that are of great interest for organic chemists. Although the transition metal-catalyzed generation of heterocyclic compounds via reactions between allene bearing a nucleophilic functionality and organic halides is well established, such a strategy has never been applied to allenamides. Thus, we set up conditions for a synthesis of 2-styryl-imidazolidinone structures through a pure domino carbopalladation-amination sequence. The same protocol, under CO atmosphere, was able to lead to interesting enone structures, while the incorporation of an iodine atom in an appropriate position into the starting allenamides permitted to access imidazoisoquinolinones. The second part of this thesis was spent in the laboratories of Prof. Giovanni Poli (Univ. Pierre et Marie Curie, Paris), where a new approach to 1,4-benzodiazepin-5-ones via a pure domino carbopalladation /allylic amination process starting from allenylamides of anthranilic acid was developed. The cyclization step is quite different from the previously described one, since the originality of this protocols lies in the fact that no phosphines as ligands are needed, as the Pd- species is stabilized by the conjoint action of BuLi and DMSO. The shorter homologues of these allenylamides were the next substrate which we focused our attention. Submitted to the same protocol, they indeed gave rise to quinazolinone structures. However, a gold-catalyzed cyclization set up onto the same substrates was much more interesting, due to its ability to lead to vinyl-substituted products. Finally, the same products can be obtained through the first example of ruthenium catalyzed intramolecular hydroamination of allenes, though this reactions still needs to be investigated for its mechanism and scope.