Reactions phosphination

Properties and Reactions. Phosphine [7803-57-2] produced in a number of ways. However, the inadvertent evolution of... 

Conventional reagents that cannot easily be removed by solid-phase extraction may be tagged in such a way that extraction by scavenger resins becomes possible. For example, for Mitsunobu reactions phosphines and azodicarboxylic acid derivatives of types 3 and 4... 

Bixchler Napiralski, Dieckmann cyclization [15], Suzuki reaction [48], Wittig reaction, ozonolysis, condensation, esterification, nucleophilic substitution [49], Henry reaction, 1.3-dipolar cyclo-addition, electrophilic addition [50], oxidation chloride -> aldehyde [50], sulfide —> sulfone [51], alcohol —> ketone, Arbuzov reaction (phosphine-phosphorox-ide) [52], reduction hydration [45], ester -> alcohol [49, 53]... 

The past year has seen the development of phosphine oxide-based olefin synthesis into a genuinely useful method that complements the Wittig reaction. Phosphine oxide-stabilized carbanions provide stereospecific routes to both (F)- and (Z)-alkenes through separation of diastereomeric intermediates the earlier problem posed by the tendency for one diastereomer to predominate has been partially overcome by the development of alternative routes which provide major amounts of each isomer. Renewed interest in the mechanism of the Wittig reaction has promoted some novel suggestions, particularly those which... 

Cobalt, nickel, iron, ruthenium, and rhodium carbonyls as well as palladium complexes are catalysts for hydrocarboxylation reactions and therefore reactions of olefins and acetylenes with CO and water, and also other carbonylation reactions. Analogously to hydroformylation reactions, better catalytic properties are shown by metal hydrido carbonyls having strong acidic properties. As in hydroformylation reactions, phosphine-carbonyl complexes of these metals are particularly active. Solvents for such reactions are alcohols, ketones, esters, pyridine, and acidic aqueous solutions. Stoichiometric carbonylation reaction by means of [Ni(CO)4] proceeds at atmospheric pressure at 308-353 K. In the presence of catalytic amounts of nickel carbonyl, this reaction is carried out at 390-490 K and 3 MPa. In the case of carbonylation which utilizes catalytic amounts of cobalt carbonyl, higher temperatures (up to 530 K) and higher pressures (3-90 MPa) are applied. Alkoxylcarbonylation reactions generally proceed under more drastic conditions than corresponding hydrocarboxylation reactions. 

Alkylation at Phosphorus. Phosphines and phosphites undergo easy quaternization. Thus methylation of tris(2,6-dimethyl-phenoxy)phosphine with MeOTf, followed by treatment of the product with sodium 2,6-dimethylphenoxide, gave methyltetrakis (2,6-dimethylphenoxy)phosphane. Methoxyphosphonium tri-flates are relatively stable intermediates in Arbuzov reactions Phosphine oxides and sulfides are alkylated. S-Methylation of chiral phosphine sulfides, followed by treatment with hexam-ethylphosphorous triamide, has been advocated as a general synthesis of optically active phosphines. ... 

Without additional reagents Borane exchange reactions Phosphine boranes from borazanes... 

In the hydroformylation-hydrogenation reaction, phosphine ligands are used in a slight excess (P/Co = 2 1) in comparison to the metal. In general, catalysts modified in this manner are less active in comparison to the unmodified complex HCo(CO)4. An excess of phosphine decreases the activity further. Corresponding trialkyl arsenic ligands produced less selective catalysts. Also, with arsines an increase in the temperature increased the yield of the alcohol over the aldehyde [39]. At temperatures of 150-190°C, almost exclusively alcohols were formed in yields of 80-85%. Polar solvents such as DMF (A/ ,A/ -dimethylformamide) can inhibit the hydrogenation of the aldehyde [40]. 

Reactions.—Desulphurization of thiirans to alkenes remains an important strategy for the preparation of hindered alkenes, e.g. (14), and is the most typical thiiran reaction. Phosphines and phosphites are the reagents that are most often used. Lithium reagents desulphurize rra s-2,3-diphenylthiiran to ( )-stilbene, while the ds-isomer is converted into a 1 1 mixture of (Z)-stilbene and the two isomers of tr-mercaptostilbene. 2-Phenylthiiran is desulphurized by cf-metallated isocyanides. Thermal extrusions of sulphur include the conversion of (15) into (16), amongst others. Desulphurizations using zinc and acetic acid, molybdenum or palladium complexes, and the oxaziridine (17) have been reported. 

A study of palladium-catalysed conjugate addition of diorganozincs to various enone types indicated that both Pd(0) and Pd(II) complexes could catalyse the reaction. Phosphine ligands such as PPhj or PBuj were effective, but only at a 1 1 Pd P ratio a 1 2 ratio caused yields to collapse. The observation is consistent with a mechanism computed for the Pd(0) case, in which the enone is simultaneously coordinated to Pd(0) and R2Zn this undergoes oxidative addition to palladium with simultaneous transmetalation from Zn to Pd, followed by reductive elimination. 

Phosphine-Catalyzed Reactions Phosphine-catalyzed [3+2] dipolar cycloaddition has been applied in an intramolecular manner, whereby three contiguous stereogenic centers, including a quaternary center, are created in a single operation (Scheme 6.27). It may be noted that the intramolecular cycloaddition is stereospecific. When the E-isomer is used as the starting material, the quaternary center formed possesses the stereochemistry consistent with the structural features of hirsutene [31]. 

Close attention has been devoted in recent years to the homogeneous catalytic reduction of N-acylaminoacrylic acids with the aid of chiral Rh-complexes. In some cases exceptionally high optical yields have been achieved in these reactions. Phosphine-Rh catalysts of the DIOP type, i. e. with chiral carbon skeleton, have been used 108, 109, 133,142,145, 146, 172, 193, 194, 234), as have catalysts with phosphine oxide ligands 409), ferrocenyl-phosphine-Rh complexes 171), bisphosphine-Rh complexes with a chiral pyrrolidine ring 3, 4), systems with chiral phosphines 216—221) and bisphosphines (222), or with a chiral P- and C-skeleton 130). 

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