Dearomatizing anionic cyclization of N-methyl-N-benzyldi(1-naphthyl)phosphinamide: a route for access to a new class of functionalized tricyclic azaphospholes with antitumor properties

The dearomatizing anionic cyclization of N-alkyl-N-benzyldi(1-naphthyl)phosphinamide 1d followed by trapping with a series of carbonyl reagents and α,β-unsaturated ketones under optimized conditions provided new tetrahydro-1H-naphtho[1,2-c][1,2]-azaphosphole 1-oxides from moderate to high yields and diastereoselectivities. In addition, two doubly dearomatized compounds as a result of double dearomatization on the two naphthalene rings of 1d have been isolated at first time. Three functionalized azaphospholes have been evaluated on three different human tumor cell lines showing growth inhibition factors (GI50) at a micromolar scale. One of these heterocycles has also shown cytostatic properties.