Phosphines reaction with amines

The addition of alkyl haUdes to phosphines is analogous to the reactions with amines. Because primary phosphonium salts are highly dissociated, the reaction proceeds to the tertiary or quartemary salts. 

However, these trends, which cannot provide an absolute scale for Lewis acidity and basicity, do not necessarily allow predictions of what kind of adducts will be formed.18 Gallane GaH3 for instance forms more stable adducts with phosphines than with amines. Consequently, reactions between H3Ga-<— NMe3 and tertiary phosphines PR3 yield the corresponding phosphine adducts. In sharp contrast, A1H3 forms significantly more stable adducts with amines than phosphines.19... 

By substitution reactions with amines, especially pyridine and o-phen-anthroline (57), and later with isonitriles (11), and phosphines and similar compounds (60), we obtained the complete series of iron(II) halide (especially iodide) compounds with one to four CO groups per molecule. 

The requirement for sodium borohydride in the nickel-catalyzed reactions with amines is presumably owing to its ability to prevent complex formation between Ni(acac)2 and the amine. Even in cases where the borohydride is not essential, its addition results in some enhancement of the rate. The role of the phosphine is to reduce Ni(ll) to Ni(0). 

Imamoto reported that Pd-catalyzed coupling of phosphine-borane with aryl halides is useful for preparation of asymmetric phosphines. Phosphines can be easily isolated from phosphine-boranes by exchange reaction with amines such as pyrrolidine and DABCO [10]. Lipshutz found that aryl nonaflates ( Nf = nonafluorobutanesulfonate) and triflates are good substrates for coupling with BHs-stabilized diaryIphosphines. Selective coupling with nonaflate without... 

Phosphine boranes would not be so popular if the borane group could not be easily removed. Two reliable methods have been developed. The first one is the treatment of phosphine boranes with amines (D) or alcohols, which act as borane acceptors. Although phosphine boranes are in general more stable than amine boranes, the presence of a large excess of a basic amine frequently suffices to displace the equilibrium and deprotect completely the phosphine. Typical amines used for this transformation are diethylamine, TMEDA, pyrrolidines, morpholine and DABCO. The reactions are usually carried out at room temperature or with moderate heating in neat amine with the exception of DABCO, which as it is a solid is typically used in toluene. 

A-Thioalkylphthalimides (215) are converted into A -alkylphthalimides by tris(dimethylamino)phosphine, providing a method of transformation of thiols into amines. Thiols react with such N-thioalkylphthalimides in a general procedure for the preparation of unsymmetrical disulphides a similar reaction with amines gives A -thio-iV -diamides. These reactions are outlined in Scheme 145. 

As compared to the direct esterifications, the amidations had a lower enthalpy of activation (ca. 79 vs ca. 102 kcal/ mol) however, the amidations were significantly endothermic (33kcal/mol) [39]. It is recalled herein that the esterifications are thermoneutral [35]. As far as such amidation reactions are concerned, it is the fact that the MW-assisted reaction of phosphinic acids and amines is of limited use and the traditional method involving the reaction of phosphinic chlorides with amines still remains the method of choice (Scheme 5). During the preparation of l-amino-3-phospholene oxides (21) by this method, an interesting side reaction was also found to take place yielding a bis(phosphinoyl) amine (22) (Scheme 6) [40]. However, using appropriate molar ratios and addition techniques, both e formation of the amino-3-phospholene oxides (21) and that of the bis(products) (22) could be optimized [40]. 

A series of thiolactones (CIII) has been obtained in yields of 58-81 % by treatment of complex XCVI with ceric ammonium nitrate in acetone (Alper and Chan, 1973). This complex exhibits a great propensity towards carbonyl insertion, and these thiolactones may also be prepared by other means such as treatment with FeClj, heating in ethanol, photochemical irradiation at 2537 A, or by reaction with amines, phosphines, alcohols, or thiocyanate ion (Alper et ai, 1974). Note that these thiolactones are dihydro derivatives of isobenzothiophenes, little-known heterocycles (Albert, 1959 Katritzky and Lagowsky, 1968), whose synthesis in two steps may now be facilitated. 

Phosphine(s), chirality of, 314 Phosphite, DNA synthesis and, 1115 oxidation of, 1116 Phospholipid, 1066-1067 classification of, 1066 Phosphopantetheine, coenzyme A from. 817 structure of, 1127 Phosphoramidite, DNA synthesis and, 1115 Phosphoranc, 720 Phosphoric acid, pKa of, 51 Phosphoric acid anhydride, 1127 Phosphorus, hybridization of, 20 Phosphorus oxychloride, alcohol dehydration with. 620-622 Phosphorus tribromide, reaction with alcohols. 344. 618 Photochemical reaction, 1181 Photolithography, 505-506 resists for, 505-506 Photon, 419 energy- of. 420 Photosynthesis, 973-974 Phthalic acid, structure of, 753 Phthalimide, Gabriel amine synthesis and, 929... 

The nucleophilic displacement reactions with azide, primary amines, thiols and carboxylatc salts arc reported to be highly efficient giving high (>95%) yields of the displacement product (Table 9.25). The latter two reactions are carried out in the presence of a base (DBU, DABCO). Radical-induced reduction with tin hydrides is quantitative. The displacement reaction with phenolates,61j phosphines,6M and potassium phthalimide608 gives elimination of HBr as a side reaction. 

Using other alkylated benzene hydrocarbons, e.g., amyl-, hexyl-, octyl-, or nonylbenzene, similar surface-active phosphinic acids are formed by reaction with PC13 in the presence of anhydrous aluminum trichloride. The resulting alkylarylphosphinic acids form stable salts with primary, secondary, or tertiary hydroxy amines or aromatic amines [166,171]. 

The reaction between a Lewis acid R3M and a Lewis base ER3, usually resulting in the formation of a Lewis acid-base adduct R3M—ER3, is of fundamental interest in main group chemistry. Numerous experiments, in particular reactions of alane and gallane MH3 with amines and phosphines ER3, have been performed [14]. Several general coordination modes, as summarized in Fig. 2, have been identified by X-ray diffraction. 

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. 

Not only N-H bonds from amines can participate in the aminolysis reaction, but also less nucleophilic urea, thiourea and biuret NH units can react with halophosphanes in an effective manner, forming the corresponding phosphinous amides with additional functionalities at the nitrogen atom [39-44]. 

Other reactions that resulted in the formation of P=N double bonds are those of NH phosphinous amides with tetrahalomethanes [106-108]. The reaction products, P-halophosphazenes 19, may be further elaborated by substituting the halogen atom with amines or Grignard reagents (Scheme 19). 

The reactions of phosphorus pentachloride and diphenyltrichloro-phosphorane with amines and related compounds are reported in Chapter 9. The n.m.r. spectra of phosphine-phosphorus pentafluoride adducts have been described (see Chapter 11 for details). 

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