Phosphines aliphatic

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. 

A method for determining the basicities of phosphoryl compounds has been decribed which is based on 31P n.m.r. chemical shift measurement and a two phase system consisting of an organic solvent and 12H sulphuric acid.245 The gas-phase protonation of aliphatic phosphine oxides have been determined by cyclotron resonance. There was a good correlation of pK4 with Kabachnik constants and HO... 

Further variations of the basic motif of 1 comprise carbene le in which the anionic ligands are trifluoroacetate rather than chloride (Fig. 2) [4d]. However, this specific compound shows a significant tendency to isomerize the double bonds of the substrates in addition to its metathetic activity. Moreover, water soluble catalysts have been developed that contain bulky aliphatic phosphine ligands with either a quarternary ammonium group (lf,g) or a sulfonate function (lh) [12]. They have been tested in the ring opening polymerization... 

Aliphatic iodine derivatives, 14 376 Aliphatic ketones, 14 563, 571, 581-585 reactions of, 16 331-332 Aliphatic monothiopolyesters, 23 739 Aliphatic nitration, 12 187 Aliphatic peroxyacids, 13 464 Aliphatic peroxycarboxylic acids, 18 463 Aliphatic phosphines, 19 60 Aliphatic polyamides (PA), 10 207-210 19 713, 739. See also Aromatic polyamides PA entries producers of, 10 210 properties of, 10 208, 209t Aliphatic polycarbonates, 24 703 preparation of, 19 798 Aliphatic polyketones (PK), 10 197 costs of, 10 222 properties of, 10 198t Aliphatic poly(monosulfide)s, 23 702-704 Aliphatic polyphosphonate dyes, 9 480 Aliphatic poly(polysulfide)s, 23 711 Aliphatic polysulfides, 23 734 Aliphatic polysulfoxides, 23 733 miscibility of, 23 735 Aliphatic polyurea preparation, carbonyl sulfide in, 23 625... 

Another group of bicyclic aliphatic phosphines has been introduced by Sasol [15], Their ligands are based on addition of PH3 to limonene (the R-enantiomer). A mixture of two diastereomeric compounds is obtained due to the two configurations of the methyl group at the C-4 position (Figure 7.9). The Lim-H compounds obtained can be functionalised at the phosphorus atom with the usual radical reactions with alkenes or substitution reactions of their conjugate bases formed after treatment with BuLi with electrophiles. 

As shown in Scheme 1, aliphatic phosphines such as P(n-Bu)3 catalyze the addition of alcohols (2) to methyl propiolate (3) [35]. The mechanism is believed to involve an initial addition of the phosphine to the C = C moiety to give a zwitterionic allenolate (I), which then deprotonates the alcohol, yielding a vinyl phosphonium salt (II). An alkoxide addition to give an enolate (III), followed by phosphine elimination gives the product 4 and regenerates the catalyst. Several experiments suggest that when alcohols are used in excess, the catalyst rests as the original phosphine [34]. 

Water-soluble, aliphatic phosphines have been synthesized for their inclusion into ruthenium olefin metathesis catalysts (28). Complexes of the type... 

B. Mohr, D.M. Lynn, and R.H. Grubbs, Synthesis of water-soluble, aliphatic phosphines and their application to well-defined ruthenium olefin metathesis catalysts, Organometallics, 15(20) 4317 4325,1996. 

This reaction takes place so readily that aliphatic phosphines must be protected from atmospheric oxygen. The triarylphosphines are more stable in this regard but still can be oxidized readily ... 

The reactions were carried out by using trans-chloro( 1-naphthyl)-bis(triphenylphosphine)nickel(II) (l, Ar = Ci0H7) complex as catalyst in the presence of various phosphorus ligands. We observed that aromatic phosphines in arylnickel(II) complexes 1 are easily replaced by aliphatic phosphines. In fact in the presence of alkylphosphines, such as P( C6Hn )3 and P(C4H9)3, cyanation did not occur. Moreover phosphites such as... 

Recent use of phosphine ligands in the areas of catalysis,3,4 pentacoordination,5,6 and oxidative-addition reactions7 has prompted investigations into variations of donor basicity, chelate chain length, and mixed sets of donor atoms. Thus, relatively accessible synthetic routes to chelating aliphatic phosphines are needed. Removal of sulfur from a diphosphine disulfide8 and subsequent preparation of NaPR2 in liquid ammonia provides a useful laboratory route to aliphatic phosphines. For example,... 

Aliphatic phosphines add to CrX2 (X = Cl, Br), yielding adducts of uncertain composition, for example [Cr(PR3) X2] (n = 1-3). With chelating diphosphines, for example dmpe, well-characterized six-coordinate complexes have been prepared. The latter have low-spin electronic confignrations. A spin-crossover situation has been found in the complex [Cr(depe)2l2] (depe = l,2-bis(diethylphospino)ethane). At ca. 170 K, this trans octahedral complex exhibits a discontin-nous spin transition from S = I (2.8 /u-b) to S = 2 (4.8 /xb). 

Secondary aliphatic phosphines are prepared by other methods, which have been described. Secondary phosphines form molecular addition compounds with boron halides. Dehydrohalogenation of diphenylphosphine-boron triiodide (or diphenylphosphine-boron tribromide) gives the dimeric phosphinoborane. The following method of preparation makes isolation of the intermediate addition compound unnecessary. Reaction of dibutyl(trimethy 1-silyl)phosphine with boron tribromide and ehmination of bromotrimethylsilane gives a dimeric phosphinoborane also. ... 

A similar reaction was reported by Ma et al. in preference to Trost s work [15]. In the isomerization of 2-ynols to a,/3-unsaturated aldehydes, the combination of a ruthenium catalyst, RuCl2(PPh3)3, and 2 equiv. of an aliphatic phosphine ligand, such as P Bu3 or P Pr3, is effective. 

Mukaiyama aldol reactions. Silyl keteneacetals undergo condensation with aldehydes under the influence of tris(2,4,6-trimethoxyphenyl)phosphine. Triphenylphosphine is slightly less efficient and aliphatic phosphines such as t-BujP are much infenior. 

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