Quinocarcin, tetrazomin and lemonomycin constitute a subfamily belonging to the family of natural trisubstituted tetrahydroisquinolines. These are powerful cytotoxic agents and have many biological activities such antitumor and antibiotics. Their structural complexity, biological interests and their low efficiency of extraction of the natural environment make these molecules attractive targets for synthetic chemists.These three molecules are constituted of differently substituted tetrahydroisoquinoline diazabicycle merged with a [3.2.1] octane common. The purpose of this project was to develop a common strategy in this subfamily and divergent with the synthesis of diazabicyclooctane first.A first strategy involving an aziridine failed to build the bicycle. This objective was achieved through a second strategy. It is based on a first cyclization of hemiaminal followed by cyclization of nucleophilic addition of a silyl enol ether of an N-acylimmonium formed in situ from a N, S-ketal.Along with this synthetic study, we developed a multicomponent reaction sequence that allows quick general access to -amidosulfides, filling a gap in the literature. Then we studied the reactivity of these compounds as simple precursors of N-acylimines in mild acidic conditions. Three reaction conditions allowed us to reach this goal: the use of stoichiometric silver acetate, phosphoric acid as catalyst and NIS in catalytic and stoichiometric amount. This last reaction is very attractive. Indeed, this sof and neutral reagent allows the efficient removal of the thiol forming the N-acylimine and its activation to be trapped in situ by a nucleophile. The yields are very high in less than 5 minutes.
