Reductions of phosphorus compounds

Silane reductions of phosphorus compounds are listed in Table 1. Mono- or dichlorophosphines and phosphoryl compounds react with Ph SiH, e.g. ... 

Phosphorus and Silicon in Waters, Effluents and Sludges [e.g. Phosphorus in Waters, Effluents and Sludges by Spectrophotometry-phosphomolybdenum blue method. Phosphorus in Waters and Acidic Digests by Spectrophotometry-phosphovanadomolybdate method. Ion Chromatographic Methods for the Determination of Phosphorus Compound, Pretreatment Methods for Phosphorus Determinations, Determination of silicon by Spectrophotometric Determination of Molybdate Reactive Silicon-1 -amino-2-naphthol-4, sulphonic acid (ANSA) or Metol reduction methods or ascorbic acid reduction method. Pretreatment Methods to Convert Other Eorms of Silicon to Soluble Molybdate Reactive Silicon, Determination of Phosphorus and Silicon Emission Spectrophotometry], 1992... 

In 1969, Fiaud and Kagan[U1 tested ephedrine boranes but achieved only 3.6-5% enantiomeric excess in the reduction of acetophenone. Itsuno et a/.[121 reported in 1981 an interesting enantioselective reduction of a ketone using an amino alcohol-borane complex as a catalyst. Buono[131 investigated and developed the reactivity of phosphorus compounds as ligands in borane complexes for asymmetric hydrogenation. 

Reduction of nitro compounds with yellow phosphorus [55] (Eq. 53). 

Alkali or alkaline-earth metal hydride reductions of P compounds are less effective than those using complex hydrides, e.g., LiAlH . Phosphorus tribromide reacts with LiH in Et,0 at O C to form a phosphorus subhydride quantitatively ... 

Ionic hydride reductions of halophosphorus compounds that are effective for phosphine syntheses are adaptable to deuteriophosphine syntheses. Lithium-deuteride reductions yield phosphorus subhydride, phosphine or alkyl- or arylphosphines ... 

Disubstituted peroxides are cleaved reductively by the same reagents as are used for hydroperoxides. The usual products are alcohols derived from the two substituents, but considerable selectivity is possible with some substrates. This is illustrated by the reduction of cyclic endoperoxides of the general formula (50) these compounds are available from the cycloaddition of singlet oxygen to cyclic conjugated dienes. The reduction of such compounds provides a good method of synthesis of cis-1,4-diols, which can be formed with retention of the double bond or with reduction of it (Scheme 29). It is also possible to prepare unsaturated epoxides by reduction with triphenylphosphine or other phosphorus(III) reagents. 

Lithiation of (31) leads to an unexpected phenomenon of NP bond cleavage and, consequently, to the reduction of phosphorus to oxidation state three from five. One NP bond is cleaved by reaction of (31) with LiN(SiMe3)2, giving the lithium adduct (35). Additionally, two NP bonds are cleaved by the reaction with MeLi or Bu"Li, leading to the previously reported compound (36). ... 

In all of this early work the general observation was made that the successful operation of the process was greatly interfered with by the rapid deterioration of the catalyst. This seemed to depend in part upon impurities present in the acetylene (phosphorus and its compounds being particularly potent poisons) and also upon the deposit of carbon on the surface of the catalyst due to decomposition reactions. When metal oxides or compounds such as, for example, molybdic acid were used, deterioration appeared to be due at least in part to the partial reduction of these compounds. In most of these cases the activity of the catalyst was restored 107 by heating it in a current of air at high temperatures (600° C.). 

A method for the reduction of phosphorus (V) to phosphorus-(III) compounds under mild conditions has been published... 

The phosphorus can also be introduced in the form of a vinylphospho-nate for copolymerization with styrene in the curing step. Polyesters of this type, with bis(2-chloroethyl) vinylphosphonate as part of the cross-linking system, were marketed for a time (173). The only use of phosphorus compounds in any significant volume in polyester resins has been that of triethyl phosphate or dimethyl methylphosphonate for viscosity reduction and flame retardancy in filled-polyester, sheet-molding compositions. 

Note 4. Reduction of nitrogen compounds prior to Kjeldahl digestion. Nitro, nitroso and azo compounds, also hydrazones, oximes and some heterocyclic compounds are not quantitatively digested by the catalysts A, B or C shown in Table 2.8. If compounds of these types are being analysed either add 0.5 g pure sucrose (or glucose) to the mixture of catalyst A or B, sulfuric acid and a suitable weight of sample (or carry out a preliminary reduction of the sample with hydriodic acid and red phosphorus as described next.)... 

Low-valent nitrogen and phosphorus compounds are used to remove hetero atoms from organic compounds. Important examples are the Wolff-Kishner type reduction of ketones to hydrocarbons (R.L. Augustine, 1968 D. Todd, 1948 R.O. Hutchins, 1973B) and Barton s olefin synthesis (p. 35) both using hydrazine derivatives. 

When saccharin is treated with diethyl phosphorothiolothionate, the 3-ethylmercapto compound is obtained, rather than the expected organophosphorus compound (77 ACS(B)460). Treatment of saccharin with phosphorus pentoxide and amines gives 3-(substituted-amino)-1,2-benzisothiazole 1,1-dioxides, via an intermediate phosphate (81ZN(B)1640). Reduction of saccharin with zinc and hydrochloric acid gives 2,3-dihydro-l,2-benzisothiazole 1,1-dioxide, the method being used to estimate saccharin in foodstuffs (75MI41701). 

In further modifications of these norprogestins, reaction of norethindrone with acetic anhydride in the presence of p-toluene-sulfonic acid, followed by hydrolysis of the first-formed enol acetate, affords norethindrone acetate (41). This in turn affords, on reaction with excess cyclopentanol in the presence of phosphorus pentoxide, the 3-cyclopentyl enol ether (42) the progestational component of Riglovic . Reduction of norethindrone affords the 3,17-diol. The 33-hydroxy compound is the desired product since reactions at 3 do not show nearly the stereoselectivity of those at 17 by virtue of the relative lack of stereo-directing proximate substituents, the formation of the desired isomer is engendered by use of a bulky reducing agent, lithium aluminum-tri-t-butoxide. Acetylation of the 33,173-diol iffords ethynodiol diacetate, one of the most potent oral proves tins (44). ... 

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