Enolates tris phosphine

The coupling of the enol triflate 703 with the vinylstannane 704[397] has been applied to the synthesis of glycinoeclepin[576]. The introduction of a (Z)-propenyl group in the / -lactam derivative 705 proceeds by use of tri-2-furylphosphine[577]. However, later a smooth reaction to give the propenyl-iactam in 82% yield was achieved simply by treating with Pd(OAc)2 in NMP or CH2CI2 for 3-5 min without addition of LiCI and the phosphine ligand[578]. 

The unsaturated c.vo-enol lactone 17 is obtained by the coupling of propargylic acetate with 4-pentynoic acid in the presence of KBr using tri(2-furyl)-phosphine (TFP) as a ligand. The reaction is explained by the oxypalladation of the triple bond of 4-pentynoic acid with the ailenyipailadium and the carbox-ylate as shown by 16, followed by reductive elimination to afford the lactone 17. The ( -alkene bond is formed because the oxypalladation is tnins addition[8]. 

It has been reported by Burgada (I09a) that highly enolized ketones form enamines when they are treated with tris[dimethylamino]phosphine. Only condensation products are formed when slightly enolized ketones are treated with this reagent. 

Geranyl chloride can be prepared from geraniol by the careful use of triphenylphosphine in carbon tetrachloride. Tris(dimethylamino)phosphine reacts with carbon tetrachloride to form the complex (42) which can be used to form the enol esters (43) from acid anhydrides. Similarly, aldehydes form the alkenes (44), and esters or amides of trichloroacetic acid are converted to glycidic esters. ... 

Optimum conditions for the coupling of the alkenyl triflates 330 with the arylstannanes 331 have been studied. Ligandless Pd complexes such as Pd(dba)2 are most active in the reaction of the enol triflate. PI13P inhibits the reaction. NMP as a polar solvent gives the best results. The use of tri(2-furyl)phosphine and Ph As in the coupling of stannanes with the halides and triflates increases the rate of the transmetallation of the stannanes to Pd, which is thought to be the rate-... 

Phosphine-catalysed annulation between aldehydes (RCHO) and ethyl allenolate (H2C=C=CHC02Et) gives 6-substituted 2-pyrones (52), proceeding via a zwitterionic (g) enolate.201 The product is derived from the -intermediate, which is favoured by the use of sterically demanding trialkylphosphines, such as tri(cyclopentyl). However, overdoing the phosphine bulk with, for example, the tri(r-butyl) derivative gives no yield. 

Very recently, new ruthenium catalysts, for example RuCl2(triazol-5-ylidene) (p-cymene) [11] and the catalytic system generated in situ from [RuCl2(p-cym-ene)]2, tris(p-chlorophenyl)phosphine, and 4-dimethylaminopyridine [12], have provided efficient catalysts for synthesis of the same type of enol ester. The regio-selective cyclization of acetylenic acids containing a terminal triple bond to give unsaturated lactones was performed in the presence of catalytic amounts of Ru(tris(pyrazolyl)borate)(PhC=C(Ph)C CPh)(PMe2iPr2) [13],... 

Starting from pent-4-yn-l-ols,the previously described catalytic system led to a mixture of lactone and cyclic enol ether [41]. However, in the presence of (Cp)ruthenium complexes bearing an electron-rich ligand such as tris(p-methoxyphenyl)phosphine in the presence of a large excess of the same ligand [system A], the selective formation of lactones was obtained. A simple modification of the catalyst precursor such as the switch to the electron-deficient... 

The catalytic system [A] based on RuCl(Cp)(tris(p-fluorophenyl)phosphine)2 (5 mol%), tris(p-fluorophenyl)phosphine (20 mol%), (BU4NPF6, 15 mol%) and N-hydroxysuccinimide sodium salt (50 mol%) led to the selective transformation of pent-4-yn-l-ols into cyclic enol ethers via intramolecular anh-Markovnikov addition of the hydroxy group to the terminal carbon of the triple bond [21],... 

Tris(dimethylamino)phosphine desulphurizes / -keto-sulphides (60) to give ketones and enol ethers as major products a mechanism involving initial... 

Tri-n-butyltin hydridelbis(dibenzylideneacetone) palladium (O)ltri (2-fury I) phosphine <-Ethylene derivs. from enol triflates C = C(OTf) C = CH... 

A dinuclear Pt complex with chelating tris( -tolyl)phosphine and bridging chloro ligands has been converted into a neutral PPhs-coordinated complex 548 and then into cationic complexes containing phosphonium-substituted enolate ligands (549, Scheme 76). Reaction with phosphorus ylides produces 550 and 551. 

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