ИСТИНА

Transition metal complexes bearing an η1--P-substituted carbene ligand – phosphorus homologues of Fischer carbenes – are still quite scarce and their reactivity remains practically unexplored. We have recently disclosed a simple and efficient route to such complexes (3, see Scheme below) upon combination of electrophilic carbyne precursors (1) and primary or secondary phosphines via a nucleophilic addition / deprotonation sequence.[1] This approach actually gave access to a continuum of -phosphonio- (2), η1--phosphino- (3), et η1--phosphidocarbene (4) complexes, for which direct use as synthons in organophosphorous chemistry is now envisioned. Indeed, the coupling of the -phosphoniocarbenes complexes 2 with secondary phosphines leads to the formation of diphosphinomethane derivatives 5 in excellent yields after demetallation by visible light irradiation (!). Cyclization of the diphosphines 5 with the arylcarbyne 1 (R = Ph) affords after deprotonation the non-symmetric 1,3-diphosphete 6, thus constructed in a highly convergent stepwise manner from two carbyne bricks and two different phosphine moieties.[