Alkylation of diphenylphosphines

Phase-transfer catalysed N-alkylation of diphenylphosphinic amide (I) is totally unsuitable in the case of easily hydrolysable organic halides, especially those containing additional functional groups (i.e. carbonyl or carboalkoxyl) which decompose readily in strongly alkaline medium. To circumvent the difficulty connected with simultaneous mono- and dialkylation of (I) under anhydrous conditions, N-(t-butyloxycarbonyl) diethyl phosphoroamidate (X), a doubly-protected ammonia derivative, was devised as a useful and superior substitute of phthalimide in the Gabriel-type synthesis of amines. 

A new general synthesis of primary and secondary amines utilizes phase-transfer-catalysed alkylation of diphenylphosphinic amide, which is readily available (Scheme 3), The alkylation step is limited to primary alkyl halides as alkylating agents, but the diphenylphosphinoyl protecting group is superior to the diethoxyphosphonyl group reported previously/... 

Reaction was complete within 5 min. In comparison, the stirred reaction takes ten times as long [104]. Alkylation of diphenylphosphines could also be readily achieved to give high yields of uncontaminated product. Previous routes to these important chelating agents had suffered from the extreme sensitivity of the secondary phosphines to air and the difficulty of its exclusion over the long periods of time necessary to obtain satisfactory yields of product. 

The alkylation of tertiary phosphines is, in general, compatible with elaborate structures bearing various functions or chiralities, as illustrated by the preparation of a phosphonium salt (18), intermediate in the synthesis of pseudomonic acid248 (reaction 17). For the preparation of dialkylphosphonium salts, diphenylphosphine can be directly alkylated, but it is more advantageous to use triphenylphosphine as the starting material,... 

Scheme 7 Schematic pathway of the synthesis of diphenylphosphine-functionalized car-bosilane metallodendrimers applied in allylic alkylation reactions...

The results from reactions with phenyllithium and phenylsodium indicated that the phosphorus-derived organophosphides were of complex structure (6). The alkyl halide reactions demonstrated the presence of structural units having two phenyl groups bonded to phosphorus, yet only small yields of diphenylphosphine were obtained on hydrolysis. Lithium diphenylphosphide was thus ruled out as an important intermediate, since it hydrolyzes cleanly to diphenylphosphine. Moreover, hydrolysis of the organophosphide from plienylsodium and phosphorus failed to give simple phosphine products at all, but reaction of the sodium... 

Similarly, activation of a coordinated alkene was suggested in Markovnikov-selective addition of diphenylphosphine to alkyl vinyl ethers promoted by Ni(II) and Pd(II) precatalysts such as NiBr2(PPh3)2. Nucleophilic attack on bound alkene, followed by loss of HX to form chelate 26 and protonolysis of the M-C bond would form the product and regenerate the catalyst (Scheme 34). This mechanism was consistent with the observation that added EtsN shut down the reaction [55, 56]. 

An ice-cooled soln. of diphenylphosphine in dry tetrahydrofuran treated with a 1.2 M soln. of butyllithium in petroleum ether (b.p. 40-60°), allyl phenyl ether added, and refluxed 4hrs. phenol (Y 78%) and allyldiphenylphosphine (Y 76%). — Anisole is cleaved much faster than phenetole and other simple alkyl phenyl ethers. F. e., also cleavage of thioethers and cleavage with diarylarsenide ions, s. F. G. Mann and M. J. Pragnell, Soc. 1965, 4120. 

The Keglevich group has continued to deal with environmentally friendly and P-heterocyclic chemistry. The solid liquid phase alkylation of P=0-functionalised CH acidic compounds was accomplished under phase transfer catalytic and microwave (MW) conditions." a-Hydroxy-benzylphosphine oxides were synthesized by the addition of diphenylphosphine oxide to the carbonyl group of substituted benzaldehydes under MW conditions." The double Kabachnik-Fields (phospha-Mannich) reaction was utilized in the preparation of bis(phosphinoxidomethyl)amines. The Diels Alder cycloadditions of 1,2-dihydrophosphinine oxides and subsequent... 

One of the main applications of dendrimers is in catalysis allowing easy recycling of the homogeneous catalyst by means of nanofiltration. Carbosilane dendrimers functionalized with diphenylphosphine groups at the periphery have been synthesized and characterized. Palladium complexes of these dendrimers have been used as catalysts in the allylic alkylation reaction. These dendrimeric catalysts can be used in a continuous process using a membrane reactor.509... 

P-phosphino-NHPs but the reverse reaction of a P-chloro NHP with diphenyl-trimethylsilylphosphine and subsequent reaction with a chloroalkane can be combined to produce high yields of P-alkyl-diphenylphosphines [74], Since the chloro-NHP is recovered in the second step, the overall reaction can be performed by employing this species merely as catalyst (Scheme 13). NMR investigations confirm that the appropriate P-phosphino-NHPs are in fact key intermediates in the resulting catalytic cycle, and it has been pointed out that P-X bond polarization represents a crucial factor for the overall acceleration of the catalyzed P-C... 

Alkylated diphosphines (R,R)-(92) and (93) were used as chiral ligands in the Pt-catalyzed hydroformylations of some alkeneic substrates. These ligands bring about a loss of catalytic activity with respect to the corresponding diphenylphosphine homolog, particularly in the case of the platinum systems. The regioselectivity favors the straight-chain (or less branched) isomer in the case of terminal alkenes with the exception of styrene the enantioselectivity is very low in all cases.320... 

Van Leeuwen et al. used several generations of carbosilane dendrimers with 4, 8, 24, and 36 diphenylphosphine end-groups (Figure 4.15) for the allylic alkylation reaction of allyl trifluoracetate with sodium diethyl 2-methylmalonate.[31]... 

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