Phosphinyl palladium

Palladium-catalysed asymmetrie allylations of various carbonyl compounds have been studied by Hiroi et al. using various types of chiral sulfonamides derived from a-amino acids. In particular, the chiral bidentate phosphinyl sulfonamide derived from (5)-proline and depicted in Scheme 1.63 was employed in the presence of palladium to eatalyse the allylation of methyl aminoacetate diphenyl ketimine with allyl aeetate, leading to the eorresponding (7 )-product with a moderate enantioseleetivity of 62% ee. This ligand was also applied to the allylation of a series of other nueleophiles, as shown in Seheme 1.63, providing the eorresponding allylated produets in moderate enantioseleetivities. 

Somewhat unexpectedly, monodemethylation of the esters (159 R=Me) proved impossible using several standard techniques. Deallylation of mono and diallyl ester analogues of (159), and of diallyl and allyl methyl [(1-acetyloxy)alkylJphosphonates was however acheived using palladium-containing catalysts, suggesting a potential wider applicability of the diallyloxy-phosphinyl group in synthesis. 

Pd bond in Me2Pd(dmpe) [dmpe=l,2-bis(dimethylphosphino)ethane] to generate phosphinate-palladium species with extrusion of a methane molecule (Scheme 40). Upon treatment the resulting palladium species with diphenylphosphine oxides, the remaining methyl-palladium bond was pro-tonated and a phosphinyl(phosphinato)palladium complex (20) was isolated. 

Diphenylphoshinotrimethylsilane and diphenylphosphinotrimethyltin can be used to phosphinylate aromatic rings under palladium(II) catalysis141 (equation 145). This opens up a new synthetic approach to arylphosphines not available from the more traditional route of adding an arylmetallic reagent to a chlorophosphine. 

Another interesting catalytic transformation involving alkynes is the hydro phosphinylation, which affords alkenylphosphine oxides [62]. The formation of hydride-phosphinito compounds is one of the key steps of the reaction. These species are formed by oxidative addition of the P-H bond of diphenylphosphine oxide to platinum(O) and palladium(O) complexes, which act as catalytic precursors. In this context, it should be mentioned that a novel method to prepare hydride-phosphinito compounds has been recently reported. The new strategy starts from 133 and involves the oxidative addition of the P-H bond of... 

Prodmgs 201a-c were synthesized from palladium-catalyzed phosphinylation of 4,4 -dimethyldihydrocoumarins 207 [139] with phosphonomethyl-//-phosphinate... 

Petrakis, K.S. Nagabhushan, T.L. (1987) Palladium catalysed substitutions of triflates derived from tyrosine-containing peptides and simpler hydroxyarenes forming 4-(diethoxy-phosphinyl)phenylalanines and diethyl arylphosphonates, J. Am. Chem. Soc., 109,2831-1... 

The synthesis of chiral vinylphosphines based upon the palladium-catalyzed hydro-phosphinylation of alkynes has been described (Scheme 4.305) [471]. As with many asymmetric palladium-catalyzed reactions, the key to this chemistry was the use of a chiral... 

Dobashi N, Luse K, Hoshino T, Kanada J, Kashiwabara T, Kobata C, Nune SK, Tanaka M (2007) Palladium-complex-catalyzed regioselective Markovnikov addition reaction and dehydrogenative double phosphinylation to terminal alkynes with diphenylphosphine oxide. 

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