Bis phosphinic acid

The Boyd-Regan methodology has been used for the preparation of various cyclic or benzylic mono- and bis-phosphinic acids. The reduction of phosphinic acids to secondary phosphines using silanes has been achieved. On the other hand, reduction of the bis-phosphinic acids with LiAlH4 led to bis-phosphines. Arylethylene-derived, enantiomerically pure amino alcohols have been evalu-... 

Different routes leading to the formation of silyl esters of phosphinic acids R2P(0)0SiMe3 have been investigated and the products characterized, and novel bis(phosphinic acid esters) can be prepared as shown in equation (50). The... 

Methylene bis phosphinates (6.745e), with a central carbon chain, can be obtained from methyl phosphinic esters (6.253), or from methylphosphonous diesters, which, like phosphites, undergo Arbusov rearrangements with condensation (6.749). Methylene bis phosphinic acid can be obtained by reaction (6.750). This compound is reasonably stable in hot water, but on boiling it eventually gives methylene bis phosphonic acid, (H0)20P-CH2-P0(0H)2 [7]. 

Colorless phosphate ester surfactants were also prepared by treating P4O,0 with an organic OH-containing compound in the presence of a phosphinic acid color inhibitor, e.g., bis(hydroxymethyl)phosphinic acid color inhibitor. Thus, 558 parts dodecanol containing 2.4 parts of phosphinic acid color inhibitor was treated with 142 parts P4O10 at 100-135°C. The phosphate ester surfactant had a VCS color value of 1, whereas a sample prepared without the color inhibitor had a VCS color value of 5. Twenty-eight similar surfactants were prepared using various alcohols and alcohol-alkylene oxide condensates [22]. 

Other cyclizations at phosphorus have been observed when certain phosphinates were used in the acid-catalyzed Mannich reaction. As observed previously with various phosphonous acid derivatives, reaction of aliphatic phosphinic acids with primary amines favored the formation of 2 1 adducts (73). Thus, glycine and other a-amino acids reacted under the typical conditions with excess formaldehyde and alkyl phosphonous acids to give the bis-phosphinylmethyl adducts 125. 

B. Reactions.—(/) Nucleophilic Attack at Phosphorus. A reinvestigation of the reaction between phosphorus trichloride and t-butylbenzene in the presence of aluminium chloride has shown that the product after hydrolysis is the substituted phosphinic acid (11), and not the expected phosphonic acid (12). Bis(A-alkylamino)phosphines have been reported to attack chlorodiphenyl phosphine with nitrogen, in the presence of a base, to give bis-(A-alkyl-A-diphenylphosphinoamino)phenylphosphines (13). In (13), the terminal phosphorus atoms are more reactive than the central one towards sulphur and towards alkyl halides. 

A variety of compounds have been examined which are in the phosphinic acid class. They include a phenyl cyclopentyl ester,184 a phosphinothioic anhydride,185 a dipheny1phosphinamide, 86 a red bis(di-t-buty1thiophosphinamide) and its selenide analogue,187 the anisylphosphor inane (67),1 88 the thioamide (68),1 89 and the phospholenium amide (69, Y = i-Pr2N).190... 

Xun, F. Golding, J. A. Solvent extraction of cobalt and nickel in bis(2,4,4-tri-methylpentyl)phosphinic acid, Cyanex-272. Solvent Extr. Ion Exch. 1987, 5, 205-226. 

Shinde, P. S. Dhadke, P. M. Solvent extraction separation of Cu(II) and Ni(H) with bis(2,4,4-trimethylpentyl)dithio-phosphinic acid (Cyanex 301). Indian J. Chem. Technol. 1996, 3, 367-370. 

Lower yields (-20%) of bis-(2-arylethyl)phosphinous acids have been generated in a similar system using KOH in polar aprotic... 

Chiral bis-phosphine acylplatinum complex 210 with a strong acid such as TfOH serves as an effective enantio-selective catalyst for aldol-type reactions of aldehydes with ketene silyl acetals (Equation (127)).486 The presence of water and oxygen in the catalyst preparation step is required to obtain the highly enantioselective catalyst. The intermediacy of a C-bound platinum enolate was suggested by IR and 31P NMR spectroscopies. 

Kang et al.6 reported a practical synthesis of an air-stable ferrocenyl bis-(phosphine) (p5, p5 )-l,l,-bis-(diphenylphosphino)-2,2 -di-3-pentyl ferrocene ([5, 5]-FerroPhos, 10a) and its application in the rhodium(I)-catalyzed enan-tioselective hydrogenation of dehydroamino acid derivatives. 

Bis[2-(3,6,9-trioxadecyloxycarbonyl)-4- phenyl]oxalate (TDPO), chemiluminescence reagent, 5 847-850 Bis(2,4,4-trimethylpentyl) phosphinic acid, 19 64... 

Selectivity for each product formation may also be controlled by an effective catalyst system. After the discovery of the reaction by Heck, Stille applied the reaction to organic synthesis, as he observed the preferential formation of [3-methoxy esters under neutral conditions and 1,2-diesters in the presence of a base. As Bianchini reported in 2001, selective formation of a,/3-unsaturated ester product is established by an addition of protic acid such as y)-TsOH in bis-phosphine/Pd-catalyzed oxidative alkoxycarbonylation. ... 

Such nucleophilic substitutions can also be carried out on analogous 1,1-di-arylamino-X -phosphorins and on oxy-bis -X -phosphorinsii4 or acetates 153, the latter can be viewed as mixed anhydrides in which phosphinic acid or acetic acid are easily displaced by nucleophiles. These reactions have a broad application in synthesis. 

J. Goossen of the Max-Planck-Institut, Muhlheim, has found Chem. Commun. 2004,724) that in situ activation of the acid with phthalic anhydride and inclusion of the bis phosphine DPE-Phos substantially slow alkene isomerization, which can be essentially eliminated by running the reaction to only 80% conversion. Both linear and branched carboxylic acids work well. 

Joseph P.A. Harrity of the University of Sheffield has reported (J. Org. Chem. 2005, 70, 207) a complementary approach to enantiomerically-pure piperidines. Alkylated azridines such as 17 are readily available from aspartic acid. Pd-catalyzed condensation of 17 with the Trost reagent 18 was found to be most effectively mediated by bis-phosphines such as dppp , 1,3-bis-diphenylphosphinopropane. The piperidine 19 was the key intermediate for the preparation of several of the Nuphar alkaloids, including 20. 

A convenient procedure for preparing dialkylphosphinic acids 62 involves addition of H-phosphinic acids and esters to conjugated double bonds via the silyl 87-89 or metal phos-phonite 61,[90 94] as illustrated in Scheme 21. The silyl phosphonite intermediates 61 (M = TMS) are typically formed either from phosphinic acids or esters using chlorotri-methylsilane or bis(trimethylsilyl)acetamide. The metal phosphonite intermediates 61 (Y = Li, Na, etc.) are prepared by deprotonation of the acids with a base such as sodium hydride, sodium methoxide, or lithium diisopropylamide. The conjugated double bonds are typically acrylic acids and esters substituted in the a-position with the appropriate amino acid side chain. After appropriate protecting group manipulations, additional amino acids... 

In contrast to phosphonic acids, H-phosphinic acids can be coupled with alcohols using carbodiimides to give H-phosphinates 83 (Scheme 31, Table 12).[63-1231 These H-phosphinates 83 afford the corresponding phosphonic acids 84 directly by oxidation with NaI04[123l or by treatment with bis(trimethylsilyl)amide followed by carbon tetrachloride, triethylamine, and waterJ63 Alternatively, as described above (Section 10.10.2.1.3), H-phosphinates may also be converted into the phosphonochloridates by oxidation with carbon tetrachloride and then coupled to nucleophiles other than water, f63-75-76 ... 

The nature of the Niu—P bond in pseudotetrahedral phosphine complexes has received much attention. With the AOM Gerloch et al. showed that phosphine bonds are characterized by a large o basicity and large it acidity corresponding to a back-donation of electrons from the nickel to the phosphorus atom in both mono and bis phosphine complexes.549,550... 

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