Α-keto Ylides Research Articles

Edge-shared [M2Cl10]2− complexes of reaction between oxophilic group 4 metal and phosphorus ylides

The reactions between oxophilic group 4 metal chlorides, α-keto ylides in THF, led to the formation of titanium, zirconium and hafnium edge-shared [M2Cl10]2− complexes (1a–3f). We describe that the reaction between MCl4 (M = Ti, Zr and Hf) with phosphorus ylides produce edge-shared [M2X10]2− complexes instead of O-coordination previously reported complexes. Adding dimethyl sulfoxide (DMSO) to these complexes in room temperature crystalline solid [M(DMSO)8] · 4Cl · mH2O · DMSO] (M = Ti (1g), Zr (2g) and Hf (3g); m = 0–3) together with phosphonium salts in mother liquid were formed. The compounds were characterized by elemental analysis, IR and 1H, 13C and 31P NMR spectroscopy.

A new conjugated addition of trialkyl phosphites and alkylidenephosphoranes to 3-ω-azideoacetyl coumarin synthesis of some 1,2,3,4-triazaphospholes, triazoles, and azido-coumarin derivatives

A new and efficient conjugate addition of trimethyl and triethyl phosphites to 3-ω-azidoacetylcoumarin (1) has been studied. The reaction proceeded smoothly at r.t. furnishing 1,2,3,4-triazaphosphole coumarin derivatives 4a, 4b in ∼75% yields. Linear substituted triazoles 10b, 11a were also obtained from the reactions of 1 with α-keto ylides, acetyl- and benzoylmethylene triphenylphosphoranes. Contrary to these results, Wittig reaction was occurred when 1 was allowed to react with α-alkoxycarbonylmethylene- and cyanomethylenetriphenylphosphoranes 7c, 7d, 7e as well as with methylidene- and benzylidenetriphenylphosphoranes 8b, 10a resulting in the formation of the corresponding olefins either as an intermediate 14b or as final products 11b, 11c, 12a. J. Heterocyclic Chem., (2011).

Phosphorus ylide-containing niobium complexes: preparation and characterization of homo- and heteronuclear compounds with an α-keto ylide ligand

The reactions have been studied between [{NbCl3(dme)}n] or [NbCl3(dme)(RCCR′)] with a heterocycle containing α-keto stabilized phosphorus ylide, 2-TCMP=[{2-thiazolylcarbonyl}methylene]triphenylphosphorane, and these reactions give the α-keto ylide-containing niobium complexes [{NbCl3(2-TCMP)}2] (1) and [NbCl3(2-TCMP)(RCCR′)], R=R′=Ph (2); R=R′=Me (3); R=R′=Et (4); R=Ph, R′=Me (5); R=Ph, R′=Et (6); R=Ph, R′=Pr (7); R=Ph, R′=SiMe3 (8), respectively. The reactivity of 5 towards different reagents has also been investigated. Compound 5 reacts with MeLi to give, through a deprotonation process of a phenyl ring, the ortho-metallated complex [NbCl2{NOSC4H2CHPPh2(C6H4)-O,N}]2 (9), with the loss of the alkyne ligand. Furthemore, 5 reacts with [AuPPh2R]CF3SO3 and AgCF3SO3 to give the heterometallic complexes [NbCl3(2-TCMP)Au PPh2R]2 (CF3SO3)2, R=Ph (10), R=C3H2SN (11), and [NbCl3(2-TCMP)Ag]2 (CF3SO3)2 (12), respectively, with the loss of the alkyne ligand in each case.

Phosphorus ylide niobium complexes; synthesis and characterization of the first α-keto ylide complexes, [{NbCl 3(ylide-O,N)} 2] and [NbCl 3(ylide-O,N) (RCCR′)] (ylide = [{2-thiazolylcarbonyl}methylene]triphenylphosphorane, NOSC 4H 2CHPPh 3). Molecular structure of [NbCl 3(NOSC 4H 2CHPPh 3-O,N) (PhCCPr) (Ph = phenyl, Pr = propyl)

Reactions of [{NbCl 3(dme)} n ] or [NbCl 3(dme)(RCCR′)] with a heterocycle containing α-keto stabilized phosphorus yl 2-TCMP = [{2-thiazolylcarbonyl}methylene]triphenylphosphorane, allowed the synthesis of the first α-keto ylide niobium complexes, [{NbCl 3(2-TCMP)} 3] and [NbCl 3(2-TCMP)(RCCR′)] respectively. The new complexes were spectroscopically characterized and the X-ray molecular structure for one of them was also determined.

Olefin oligomerization with nickel [formula omitted] chelate complexes

Various α-keto ylides were reacted in situ with (COD) 2Ni and the solutions obtained were applied in ethylene oligomerization/polymerization. It could be shown that changes in substituents of the P O chelate part drastically influence the product distribution of the oligomers/polymers. In the case of MePh 2PCHCOPh, EtPh 2PCHCOPh, and CyPh 2PCHCOPh, the maximum molecular weight occurs at about 2.8 (logarithm scale). However, in the case of nMenPh 2PCHCOPh, it occurs at 3.3. The molecular-weight dispersions ( M w / M n ) increase in the following order: RPh 2PCHCOPh: R = Me<R = Et<R = Cy<R = nMen In this way a handle via the PO -ligand is given to tailor the steepness of the Schulz-Flory type distribution.