Diastereoselective synthesis of new spirocompounds

The Buchwald amination is a very important reaction to prepare biologically compounds, such as indole carboline ring systems. As part of a program aiming the discovery of new compounds with antineoplastic properties, we have prepared new spirocompounds in a diastereoselective manner by addition of an organomagnesium compound to chiral tert-butanesulfinyl imines, followed by intramolecular cyclization. All (RS) or (SS)-sulfinyl imines were obtained from commercial tetralones and chiral sulfinil amines employing titanium tetroxide under microwave. The cristaline structure obtained by X-ray showed the stereochemistry of the chiral center after the nucleophilic addition. All enantiomers of spirocompounds were obtained after the removal of the chiral auxiliary in acid conditions, followed by intramolecular C-N bond catalyzed by palladium acetate in toluene in a pressure tube in good yields.