Phosphiranes as Ligands: Tungsten(0) and Palladium(0) Complexes of Phosphirano[1,2‐c][1,2,3]diazaphospholes

Abstract

Phosphirano [1,2-c][1,2,3]diazaphospholes 5, which feature a strongly pyramidalized phosphorus atom at a ring fusion position, were identified as a new type of phosphane ligands for transition metals. The derivatives 5a-c smoothly form W(CO) 5 complexes, which are thermally quite stable -in contrast to the known lability of various carbonylmetal complexes of simple phosphiranes. In the temperature range 120-150°C, they undergo a clean decomplexation in toluene solution. Bicyclic phosphiranes 5a and 5b, but not the acceptor-substituted derivative 5c, readily react with the [(E,E)-

Equilibrium Study of Pd(dba)2 and P(OPh)3 in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol

“… 10 Several examples of Pd(dba)L n ( n = 1, 2) complexes of dba and phosphorus ligands have been isolated and characterized. 11 …”

Asymmetric 1,3-dipolar cycloaddition reaction of chiral 1-alkyl-1,2-diphospholes with diphenyldiazomethane

“…40 The sum of bond angles around P2 (S(:P2) ¼ 243.1 ) of 5a reects strong pyramidalization of the environment at the phosphorus atom comparable with those for other bicyclic phosphiranes. 26,41,42 Phosphiranes are 3-membered cyclic phosphines with unique stereoelectronic properties, (smaller cone angles and higher inversion barriers compared with their acyclic analogues) and are thought to be poorer s donors and better p acceptors, 40 but their use as ligands in metal-catalyzed reactions is rare. 43 Chiral phosphiranes are especially rare; [44][45][46][47] therefore, the convenient asymmetric cycloaddition reaction reported here is potentially useful for expanding their limited applications in asymmetric catalysis.…”

New aspects of phosphirane chemistry

“…Since then, several other theoretical studies Chapter 1 Short Review on Phosphirane: Structure, Reactivity and Synthesis 4 have been carried out at different levels of theory and they are in remarkable agreement with the thermodynamical parameters presented above. [29][30][31][32][33] 1.3 Phosphiranes: Reactivity…”

“…More recent examples of using phosphiranes in transition metal catalysed reactions can be found in the work of Maas and co-workers. 92 Phosphirano-diazaphospholes, previously prepared by Arbuzov et al, 78 has been introduced as ligands in palladium-catalysed Suzuki crosscoupling of 4-bromotoluene with benzeneboronic acid. These compounds mark the first isolated palladium complexes of phosphiranes ( Fig.…”

“…32 Hence, ordinary phosphiranes are known to coordinate to transition metals, other than tungsten and molybdenum, to give stable complexes. [33][34][35][36] However, phosphirane 14 is discovered to be a poor ligand since stirring of 14 with Pd(OAc) 2 , Rh(CO) 2 (acac) or RuCl 3 at room temperature led to decomposition and no reaction took place with Pd 2 (dba) 3 .…”