Metallacycle transfer routes to main-group phosphacycles

The employment of phosphazirconacycles in metallacycle transfer reactions is a facile method for the synthesis of main-group phosphacycles. Reactions of Cp(2)Zr(PPh)(3) (1), Cp(2)Zr(P(R*)C(Ph)=CPh) (2), and Cp(2)Zr(P(Mes)P(Mes)C(Ph)=CPh) (3) with various main-group dihalides results in cleavage of TM-MG bonds and formation of new MG-MG bonds. Triphosphanato complex I reacts with PhPCl(2) or (t)Bu(2)SnCl(2) to yield (PPh)(4) (4) and (t-Bu)(2)-Sn(PPh)(3) (7), respectively. Reaction of phosphametallacyclobutene 2 with PhPCl(2) results in the formation of the unsymmetrically substituted 1,2-diphosphetene P(Ph)P(R*)C(Ph)=CPh (5), while reaction with PhBCl(2) yields PH(C6H2-(2-CH2C(CH3)(2))-4,6-t-Bu(2))B(Ph)CPh=CPh (8), the product of ring expansion via C-H activation. Phosphametallacyclopentene 3 reacts with PhPCl(2) to furnish the unsymmetrically substituted 1,2,3-triphospholene P(Ph)P(Mes)P(Mes)C(Ph)=CPh (6). Advantages to such metallacycle transfer reactions include (i) facile accessibility of main-group derivatives where conventional syntheses are laborious, tedious, and/or fraught with safety issues, (ii) selective control over molecular fragments, and (iii) new routes to novel main-group compounds.