P and S-centred reactions in a thiazole-fused 1,4-diphosphinine

Starting from a tricyclic, thiazole-2-thione-based 1,4-diphosphinine, the scope of both P- and S-functionalisations was explored. 1,4-addition reactions at the central ring were investigated, furnishing 1,4-dihydro-1,4-diphosphinines. Additionally, [4+1]- and [4+2]-cycloadditions with both carbon- and heteroatom-based substrates were performed, studying the tolerance and stability towards the bridge. The obtained 1,4-diphosphabarrelenes were examined in both P-oxidative and S-reductive fashion by synthesising P(V) moieties and by studying the desulfurisation potential of the thione moieties in 1,4-diphosphabarrelenes. Experimental observations were backed by theoretical investigations using density functional theory (DFT), gaining a deeper insight into the electronic nature of 1,4-diphosphinines and related compounds.