Phosphines and their derivatives

With rare exceptions, such as [Fe(bipy)3]°, oxidation states lower than +2 are represented only by carbonyls, phosphines, and their derivatives. These will be considered together with other organometallic compounds in Section 25.3.6. 

Transition metal complexes of cyclic phosphines and their derivatives. D. G. Holah, A. N. Hughes and K. Wright, Coord. Chem. Rev., 1975,15, 239-278 (91). 

Phosphines and their derivatives are known to be very useful ligands toward transition metals and a variety of complexes with phosphine as a ligand have been prepared for all kinds of transition metals. If one of the substituents on a coordinating tertiary phosphorus compound is abstracted as an anion, it would form a cationic phosphenium complex. Actually this strategy has been widely used, and halide, hydride, and alkoxide have been abstracted as an anion by an appropriate Lewis acid. An alternative method to prepare cationic phosphenium complexes is a direct reaction of a phosphenium cation with a transition metal complex having appropriate... 

The one- and three-bond H-C couplings of the Me2N group in 8-dimethylamino-napht-l-yl phosphines and their derivatives have been found by Schiemenz et alP to be useful indicators of the N-P interactions in these compounds. 

The reaction of phenyl(2,4,6-triniethylphenyl)phosphine with a substituted ben-zoquinone in the presence of a chiral phosphapaUadacycle complex 252a as a catalyst and triethylamine in chloroform at —45°C proceeded in a new type of addition manner to give a high yield of a 4-hydroxyphenyl phenyl(2,4,6-trimethylphenyl)phosphinite (5p)-253 with 98% enantioselectivity, which is a versatile intermediate readily convertible into various phosphines and their derivatives with high enantiomeric purity [168]. The asymmetric stepwise double hydropho-sphination reaction of bis(enones) 254 with phenylphosphine and 252b allowed intermolecular construction of chiral tertiary bulky / -heterocycles 255 in one pot in high yields (Scheme 80) [169]. 

Pietrusiewicz KM, Zablocka M. Preparation of scalemic P-chiral phosphines and their derivatives. Chem. Rev. 1994 94 1375-1411. 

Malysheva SF, Sukhov BG, Larina LI, Belogorova NA, Gusarova NK, Trofimov BA (2(X)1) Reaction of phenylacetylene with primary phosphines as a convenient way to nonsymmetric tertiary phosphines and their derivatives. Russ J Gen Chem 71 1907-1911... 

A differential vapour-pressure technique has been used to determine the molecular weights of phosphonic and phosphinic acids in 95% ethanol. Cryoscopic and n.m.r. studies have been made on solutions of phosphinic acids in sulphuric acid and oleum. Mass spectrometry has indicated the ready formation of phosphinylium ions after electron bombardment of phosphonic and phosphinic acids and their derivatives. However, the cryoscopic results in sulphuric acid indicated that reaction did not proceed beyond protonation, and the n.m.r. study on oleum solutions suggested that sulphonation occurred. 

The first P-chiral hydroxy phosphoryl compounds that were enzymatically resolved into enantiomers were o-hydroxyaryl phosphines and their oxides 75. The resolution was achieved via enzyme-assisted hydrolysis of their O-acetyl derivatives 74, the most effective enzymes being CE and Upase from C. rugosa (CRL) (Equation 35). The highest enanfioselectivity was observed in the case of naphthyl derivatives (Equation 36), having a P=0 moiety. ... 

A similar quantitative treatment of sulphoxides as hydrogen bonding acceptors has been obtained by comparing the IR frequency shift Avo of the C—I bond in an acetylenic iodide such as IC=CI (Av,, ) due to formation of a C—T complex with phenol in various bases. This investigation suggests that sulphoxides belong to the same family as carbonyls, phosphine oxides, arsine oxides and their derivatives . 

Reactions and Properties of Phosphonic and Phosphinic Acids and their Derivatives.-A free radical mechanism has been proposed to account for the cleavage of the phosphorus-carbon bond in the alkylphosphonic acids (155) by E coli to give a mixture of alkane (methane only, from methylphosphonic acid) and terminal alkene. 

All the above structures contain the P—C—O—B fragment. Among boryloxyalkylphosphines and their derivatives with an exocyclic phosphorus containing group, (123)—(125) are reported (92IZV196). Such compounds were obtained from secondary phosphines, aromatic aide-... 

Phosphonic and Phosphinic Acids and their Derivatives.—Further fundamental information on important reactions for preparing phosphonic acid derivatives has... 

In a study which is relevant to the mechanism of hydrolysis of phosphonium salts, Glaser and Streitwieser297 studied the ions H4PO- and H3PFO- and their derivatives with Li +, NH4 and HF at the 6-31G level augmented by diffuse functions. They found that the structures of the anions are those of a hydride or fluoride ion solvated by or complexed with phosphine oxide, rather than phosphoranes297. A very important point is that earlier studies with diffuse functions yielded the pentacoordinated phosphoranes which they judged297 to be computational artifacts of the small basis set. 

The biological properties of phosphorus amino acid analogues (and their derivatives) depend upon their stereochemistry. Consequently, numerous methods for obtaining these compounds in stereochemically pure form have been developed. Two excellent review articles summarize the work performed prior to 1993. 3,4 Resolution of racemates continues to be a useful approach for obtaining optically pure aminoalkylphosphonic and -phosphinic acid derivatives (vide infra), but most of the newer literature describes asymmetric syntheses of these compounds.15-17 Two methods for resolution and one for asymmetric synthesis are described (vide infra) they have been selected since they are relatively easy to perform, work with a variety of side chains, can be carried out on a reasonable scale with readily available starting materials, and produce products of high stereopurity. However, just as in traditional amino acid chemistry, each side chain introduces its own complications, and in many cases, especially for more complex analogues, other methods may be preferred. 

The Michaelis-Arbuzov reaction is the most used and well-known method for the synthesis of phosphonates and their derivatives and may also be used to synthesize phosphinates and tertiary phosphine oxides. The simplest form of the Michaelis-Arbuzov reaction is the reaction of a trialkyl phosphite, 3, with an alkyl halide, 4, to yield a dialkyl alkylphosphonate, 6, and new alkyl halide, 7 (Scheme 2). During this transformation the phosphorus atom of a ter-valent phosphorus(III) species (3) acts as a nucleophile resulting in the formation of an intermediate alkoxy phosphonium salt 5, containing a new [P—C] bond. The precise structure of the intermediates 5 is a subject of debate—as reflected by common reference to them as pseudophosphonium salts —with a penta-coordinate species (containing a [P—X] bond) being proposed and detected in some cases.18 Decomposition (usually rapid under the reaction conditions) of the intermediate 5 by nucleophilic attack of X- on one of the alkyl groups R1, with concomitant formation of a [1 =0] bond yields the product pentavalent phosphorus(V) compound (6) and the new alkyl halide, 7. 

Vinylation of various azoles (pyrrole, indole, carbazole, and their derivatives) with vinyl bromides catalyzed by palladium/phosphine complexes results in the A -vinylazoles in 30-99% yields (Equation 49) <20020L623>. This reaction with cis- and /ra r-P-bromostyrenes is stereospecific giving the respective products with full retention of configuration. 

---