Catalysis phosphine

Aryidehalogenation - Kumada-Corriu Reaction using Ni(ll)-Phosphine Catalysis... 

For the hydroformylation, (PPli j) Rli( H)(CO) with host 11 was used as the catalyst. An excess of PPhj (stemming from the catalyst precursor) was needed to avoid isomerization, as was found when phosphine-free precursors were used (at the concentrations used even bidentates should be added in excess to prevent substantial exchange with carbon monoxide). Linear to branched ratios of 2 1 were obtained and no isomerized alkene could be detected. These results are similar to those obtained by Kalck and coworkers [41]. As expected, catalysis for 11 is slower than that for (PPh3)3Rh(H)(CO) as the host is a bidentate phosphine catalysis with (PPh3)3Rh (H)(CO) strongly depends on the concentrations of rhodium and PPh3 and comparison of the rates of the two systems does not make sense. 

Figure 4. Reaction sequence of linoleate and conjugated linoleate carboxylation by palladium chloride-phosphine catalysis...

Small-Molecule Inhibitors of GGTase-I from the Heterocycle Library Derived from Phosphine Catalysis... 

Cruz, D., Wang, Z., Kibbie, J., Modlin, R., and Kwon, O. (2011). Diversity through phosphine catalysis identifies octahydro-l,6-naphthyridin-4-ones as activators of endothelium-driven immunity. Proc Natl Acad Sci USA 108 6769-6774. 

Using a split-and-pool combinatorial synthesis strategy, Tamanoi and coworkers developed a library of approximately 4000 heterocycles generated from resin-bound allenoates by means of phosphine catalysis [36,37]. This library was initially screened to identify GGTase I inhibitors (Table 8.1), and some potent GGTase I inhibitors with novel... 

The kinetics and mechanism of rhenium-catalyzed desulfurization of thiiranes was studied experimentally and by means of computation <2006IC5351>. The oxorhenium dimer MeReO(edt)2 (X), where edt= 1,2-ethanedithiolate, was found to catalyze the transfer of S from thiiranes to triarylphosphines and triarylarsines. In the case of phosphines, catalysis was less effective because they converted the dimer catalyst rapidly to MeReO(edt)PAr3, a less effective catalyst. The rate law for AsArs, which did not transform the catalyst, was v = [thiirane][X] with k = 5.581 mol s at 25°C in CDCI3, for X = cyclohexene sulfide. The value of was 10.0 0.9kcalmoP, while AY was —21 3calK moP. The proposed mechanism is shown in Scheme 6. 

Mika (22) proposed the complex intermediates in triaryl phosphine catalysis as ... 

Investigated tertiary phosphine catalysis of phosphine ligand exchange, and cis- trans isomerization. Results confirm consecutive displacement mechanism for isomerization via an ionic intermediate [PtXL3j X ... 

Attempts to add acrolein to aetivated olefins led to polymerization, but methaerolein, crotonaldehyde and cinnamaldehyde reaet normally with acrylates and aerylonitrile (Scheme 1.46). ° Upon treatment of these a,jS-unsaturated aldehydes with methyl vinyl ketone in the presenee of DABCO, the self-eondensation product 3-methylenehepta-2,6-dione was obtained exclusively some MBH adduct was isolated with phosphine catalysis (Scheme 1.46). In addition, crotonaldehyde does not add to phenyl vinyl sulfone. ... 

Advances in nucleophihc phosphine catalysis of alkenes, aUenes, alkynes, and Morita—Bayhs—Hillman alcohol derivatives (mainly, reactions leading to various heterocycles) 13CC11588. 

Lu XY, Zhang CM, Xu ZR (2001) Reactions of Electrrai-Deficient Alkynes and Allenes Under Phosphine Catalysis. Acc Chem Res 34 535... 

Ketene [2 + 2] cycloaddition with disubstituted ketones or aldehydes with phosphine catalysis gives P-lactone formation with a preference for the traws-diastereomer (Scheme 4.32). The formation ofphosphonium eno-late intermediates was monitored using NMR, and based on the NMR observation of the intermediates a mechanism was proposed in which the phosphonium enolate 158 reacted with a second molecule of the ketene forming intermediate 159, which then was acylated by the aldehyde followed by loss of 158 and formation of the product p-lactone. The use of the chiral phosphine catalyst BINAPHANE gave enantioselective product formation. 

Some additional points may be made here in regards to how Sorokin and Shode s findings apply to tertiaiy phosphine catalysis of the epoiQr-phenol reaction. 

Scheme 26.2 Selected examples of phosphine catalysis in cooperation with palladium and silver catalysis.

The MBH reaction was also discussed in a general review covering nucleophilic phosphine catalysis. 2 ... 

In accordance with this mechanism, the catalyst containing the reduced platinum interacts with a monomer molecule to form a 5-membered intermediate, which in turn interacts with the next monomer molecule to give a 9-membered cyclic Pt-containing intermediate. The latter forms the stable dimer (as in the case of Pt-phosphine catalysis) via reductive elimination. When phosphine ligands are absent, the approach of the monomer to the Pt-center becomes apparently much easier therefore, it can efficiently interact with the Pt-cyclic intermediate to produce the final polymer. 

---