Diarylphosphine oxides

Electrophilic Reactions.— Various substituted diarylphosphine oxides have been prepared by the reaction of dibutyl phosphite with the corresponding aryl Grignard reagent. 

Alkylbenzenes react analogously isomer proportions in the products are reported by Baldwin and his co-workers.153 The yield of aryldichlorophosphine decreases rapidly with increasing alkyl substitution of the ring it is already zero with mesitylene. As a variation of the process, the diarylphosphine oxides, together with small amounts of the diarylphosphinic acids, can be obtained by hydrolysis of the insoluble POCl3/AlCl3 complex. 

General procedure for the preparation of diarylphosphine oxides from mesitylene, durene and pentamethylbenzene 154 The hydrocarbon (0.3 mole) is treated with phosphorus trichloride and aluminum chloride as in the preceding prescription. After addition of the phos-... 

Ethylbenzene gives no diarylphosphine oxide, but instead 52 % of dichlorophosphine and 36 % of diarylphosphinic acid. 

Cyanations. Aluminum complexes with diarylphosphine oxide groups possev cyanation of aldehydes and imines- with in a manner analogous to the Reisser asymmetric Strecker synthesis is applic reactivity of Me SiCN than HCN in the p catalytic amount while supplying stoichica... 

Cyanadons. Aluminum complexes of BINOLs (1) that are armed at C-3 and C-3 with diarylphosphine oxide groups possess both Lewis acid and base centers. Asymmetric cyanation of aldehydes and mines with MeaSiCN, and of quinolines and isoquinolines in a manner analogous to the Reissert reaction is successful (ee 70-90%). The asymmetric Strecker synthesis is applicable to conjugated aldimines and the higher reactivity of Me SiCN than HCN in the presence of 10 mol% of PhOH enables its use in catalytic amount while supplying stoichiometric HCN as the cyanide source. 

The kinetics of the oxidation of diarylphosphine oxides with perbenzoic acid have been investigated and the kinetic deuterium isotope effects... 

Dialkyl hydrogenphosphonates provide diarylphosphine oxides conveniently as shown in the illustration. 

The interaction of a phosphinothioic acid (or a dialkyl phosphorothioic acid) with an alkyl isocyanide yields the corresponding A-alkylthioformamide together with a monothio anhydride (reaction 21) ". A further interesting sequence commences with the interaction of a diarylphosphine oxide, R2P(0)H (R = Ph or p-Tol) with HCNS. It is known that such... 

Reaction of 2-bromobenzaldehyde (39) with diarylphosphine oxide using Pd(OAc)2 and DPPP afforded the mixed triarylphosphine oxide 40, which was converted to the chiral phosphine ligand 40a [9]. 

The similar reaction of diarylphosphine oxides with aryl halides and triflates has been used more recently to prepare a variety of ligands for asymmetric catalysis. Many of these reactions involve additions of secondary phosphine oxides to di- or monotriflates derived from binaphthol because the triflates are more accessible than 2,2 -l,l -dibro-mobinaphthol. Workers at Syntex described a procedure to use the ditriflate of binaphthol to prepare mixed phosphine oxide, hydroxo ligands, and the monophosphine oxide, bi-naphthyldiphenylphosphine oxide. Hayashi then developed a route to a number of chiral monodentate phosphine ligands with a 2-(diphenylphosphino)-2 -alkoxy-l,l -binaphthyl structure (Eq. Reaction of the ditriflate with diphenylphosphine oxide in the... 

This section describes selected arylations of phosphorus, sulfur, and halide nucleophiles under metal-free and metal-catalyzed conditions. Arylations of other nucleophiles, e.g., selenium and tellurium, have been reviewed previously [4]. Aryl phosphonates [ArPO(OR)2] can be synthesized by arylation of phosphite anions with diaryliodonium salts and NaH in DMF at 70-80 °C [158]. A copper-catalyzed arylation of various phosphorous nucleophiles, e.g., diarylphosphine oxides and //-phosphonates, was recently reported to proceed at room temperature. The observed chemoselectivity with unsymmetric salts was opposite to the general trend in metal-catalyzed reactions (see Sect. 2.1), which was explained by a radical mechanism [159]. 

A palladium complex-catalysed arylation of diarylphosphine oxides was also reported. Deoxygenation provided a novel P-ligand (Scheme 20). ... 

While diphenylphosphine oxide is used in most HW reactions, attempts have been made to utilize other phosphine oxides in order to enhance Z-selectivity. For example, ortHo-substituted diarylphosphine oxides such as (anisyl)2P(0)CHPr Li have been used to produce complete Z-selectivity [53]. Dibenzylphosphole oxides 15 have also been utilized by several researchers in an attempt to enhance stereoselectivity [51, 54, 55]. 

Two independent research groups elaborated the synthesis of phenanthridin-6-yl-diarylphosphine oxides by the oxidative cyclization of 2-isocyanobiphenyls with diarylphosphine oxides (Schemes 25 and 26). ... 

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