Phosphoric amides

Me3Si)2NH, Me3SiCl, Pyr, 20°, 5 min, 100% yield. ROH is a carbohydrate. Hexamethyldisilazane (HMDS) is one of the most common sily-lating agents and readily silylates alcohols, acids, amines, thiols, phenols, hydroxamic acids, amides, thioamides, sulfonamides, phosphoric amides, phosphites, hydrazines, and enolizable ketones. It works best in the presence of a catalyst such as X-NH-Y, where at least one of the group X or Y is electron-withdrawing. ... 

Fluorinated organosilicon compounds may be prepared from readUy available fluorohalocarbons by using phosphorous amides [84, 85, 86] or tetrakis(dimeth-ylamino)ethylene [57] for the generation of the fluoroorganic nucleophiles (equations 61-69). 

The kinetics of the alkyl-halide-promoted phosphazene -> phosphor-amide rearrangement ... 

Tetrazolides can also be formed from phosphoramidites (phosphorous amides) by reaction of tetrazoles in the presence of p-dimethylaminopyridine [ 105]... 

Cyclic phosphoramidates (phosphoric amides) were obtained by the reaction of amino alcohols with a phosphoric diimidazolide.tl933,[2]... 

The formation of 151 from the phosphonate 171 could be proved only by indirect means. Electron-rich aromatic compounds such as N,N-diethylaniline and N,N,N, N -tetraethyl-m-phenylenediamine U0 1I9> and N-methylaniline 120> are phosphorylated in the para- and in the ortho- plus para-positions by 151. Furthermore, 151 also adds to the nitrogen lone pair of aniline to form the corresponding phosphor-amidate. Considerable competition between nucleophiles of various strengths for the monomeric methyl metaphosphate 151 — e.g. aromatic substitution of N,N-diethylaniline and reaction with methanol or aromatic substitution and reaction with the nitrogen lone pair in N-methylaniline — again underline its extraordinary non-selectivity. 

The hydrochloric acid is removed by the strong tertiary base, methyldibutylamine, which has a soluble hydrochloride. In B.P. s 631,549 and 652,981 it was shown that compound (II) could be prepared by the action of dimethylamine on P0C13 in chloroform containing an excess of methylbutylamine. The further reaction with water is very conveniently carried out in the same system by adding an excess of aqueous sodium hydroxide solution. The chloroform layer contains the tertiary amine and (I). The solvent and amine are stripped off leaving the product. Side reactions take place, and the commercial product also contains some triphosphoric pentadimethylamide (I A) and smaller amounts of other phosphoric amides. The compound (I A) is itself also a valuable systemic insecticide. 

N3P3C16 and DMSO undergo a complex series of reactions leading to phosphor-amidic acids (Scheme 13).136 N3P3Cl3(OH)3 was isolated and characterized as its... 

Diethyl A-alkylphosphonamides, obtained by the Atherton-Todd procedure (see procedure 5.1.13) are (V-alkylated under strongly basic two-phase conditions at reflux temperatures [56], The procedure is obviously limited to alkali-stable reagents and a better route involves the initial formation of the N-sodio salt of the phosphor-amidate, followed by alkylation under essentially neutral conditions (Table 5.28) [57],... 

The choice of these derivatives, namely, those formed from amines of moderate strength, appears to be the best compromise for the synthesis to be effective. Although the susceptibility of phosphor-amidates to attack by nucleophiles increases with enhancement of the basic strength of the parent amine,279 280 the reverse trend is observed for the yields of nucleoside 5 -phosphoramidates when they are prepared from nucleoside 5 -phosphates by condensation with the appropriate amines through the action of N,N -dicyclohexylcarbodi-imide.279... 

This conclusion has been drawn by Moffatt and Khorana,2 based on limited data. A subsequent, more detailed study [R. K. Ledneva, N. N. Preobrazhenskaya, Z. A. Shabarova, and M. A. Prokof ev, Molek. Biologiya, 5, 264 (1971)] clearly shows an unexpected decrease in the rate of the acid hydrolysis of the phosphor-amidates derived from strong amines. If a similar order of reactivities exists for the pyrophosphate synthesis, the phosphomorpholidate derivative seems close to being the most active. 

Kraus et al.75 78) in Israel fabricated new aromatic phosphoric amide-carboxamide copolymers, which gave membranes high thermal stability, flame resistance, and salt rejection. Thus a copolymer was prepared from N,N -bis(3-aminophenyl)-N"-phenylphosphoric triamide 25, m-phenylenediamine and isophthaloyl chloride in... 

Related catalysts for asymmetric borane reduction of ketones are open chain and cyclic phosphoric amides, in the oxidation state +3 or +5 (Scheme 11.3) [10, 11]. Early examples are the phosphonamides and phosphinamides 5a and 5b of Wills et al. [12] and the oxazaphospholidine-borane complex 6a of Buono et al. [13]. In the presence of 2-10 mol% catalysts 5a,b, co-chloroacetophenone was reduced by BH3 SMe2 with 35-46% ee [12]. For catalyst 6a a remarkable 92% ee was reported for the catalytic reduction of methyl iso-butyl ketone and 75% ee for acetophenone... 

Phosphoric amide catalysts for the borane reduction of ketones ... 

In metal-free catalysis enantioselective ring-opening of epoxides according to Scheme 13.27 path B has been achieved both with chiral pyridine N-oxides and with chiral phosphoric amides. These compounds act as nucleophilic activators for tetrachlorosilane. In the work by Fu et al. the meso epoxides 71 were converted into the silylated chlorohydrins 72 in the presence of 5 mol% of the planar chiral pyridine N-oxides 73 (Scheme 13.36) [74]. As shown in Scheme 13.36, good yields... 

Although carboxylic as well as phosphoric esters are widely utilized in nature, phosphoric amides do not parallel their carboxylic counterpartners as the widespread biological struc -tures. This is most likely due to the low stability of the P(0)-N bond under acidic conditions a property resulting from the different bonding at the phosphoramidate function, relative to the carboxylic system. 

IR studies reveal that phosphoric amides (5) have a high tendency for self-association resulting in the formation of the hydrogen - bonded dimers (6) ... 

As a consequence of the different electronic interactions within the phosphoramidate group, P-N bond cleavage in phosphoric amides, contrary to the behavior of analogous carboxylic compounds, is accelerated by the electron - donation at the nitrogen atom. 

Dimethoxy-l-indanone l-Benzyl-4-piperidinecarboaldehyde Hexamethyl-phosphoric amide... 

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