Phosphine imines azides

In general, azides are more easily available than nitro compounds by SN2 reaction of the corresponding halides. Thus, the direct conversion of an azide into a nitro group is useful for the synthesis of nitro compounds. Corey and coworkers have reported the easy conversion of azides to nitro compounds via ozonolysis of phosphine imines (Eq. 2.70).139... 

Addition reactions of silylphosphines to imines have been reported, 4 as illustrated for diethyl(trimethylsilyl)phosphine (70). Organic azides react with germylphosphines by an insertion pathway,65 as shown for various phenyl(trimethylgermyl)phosphines (71). The initial products (72) isomerize to phosphine imines on heating.66... 

Primary and secoiidary nitroalkanes. A new route to nitro compounds involves conversion of azides to phosphine imines by reaction with triphenyl- or tri-n-butylphos-phine at 25—35° followdd by ozonolysis in CHiCE at — 78°. Presumably the initial ozonidc is converted into a nitfoso compound, which is then oxidized to the nitro compound... 

Macromolecules with carbodiimide linkages in their repeat units are obtained from aliphatic and aromatic diisocyanates using a phospholene oxide catalyst. However, instead of linear polymers, only crossUnked thermosets are obtained in this manner. In contrast, linear polymers with pendant carbodiimide units are obtained from poly(vinyl azide) by subsequent reaction with triphenylphosphine to formpoly(phosphine imines) followed by reaction with monoisocyanates to generate the Unear poly(carbodiimides). 

Linear carbodiimides with pendant carbodiimide groups are obtained by reacting polymeric azides derived from vinyl azide 33 with triphenylphosphine to form poly(phosphine imines) 34, which are subsequently converted to polycarbodiimides 35." ... 

The phosphides and arsenides of the elements M—PRR and M—AsRR are well known for main group elements, but transition metal analogues are more unusual. Insertion reactions were not widely explored until recently, but examples are given in reactions (j) and (k) (X = O or S) ° and (l) (n) (X = or As ) and (m) are effectively oxidative insertions of a nitrene, or specifically PhN into an Sn-P or Sn-As bond, and thus represent an extension of the Staudinger reactions whereby a phosphine or arsine is treated with an azide, and thereby converted into a phosphine-imine or the arsine analogue, as follows ... 

Ligands have also been attached to polyethylene glycol so that they can be recovered for recycle by the foregoing methods. A phosphine isocyanate has been reacted with polyethylene glycol for use in the Staudinger reaction with alkyl azides to form a phosphine imine.173 An alkaloid has been attached to the monomethyl ether of polyethylene glycol for use in the Sharpless asymmetrical dihydroxylation of olefins. The reaction was complete in the same time, with no decrease in yield or enantioselectivity, as when the alkaloid was used by itself.174 (Asymmetrical reactions are covered in Chap. 10.)... 

A synthesis of 2,3-diarylpyrroles was based on the use of a difunctional phosphine imine which is capable of both Wittig and aza-Wittig condensation. <94J0C4551> The reagent is prepared from benzotriazole, formaldehyde, sodium azide and triphenylphosphine which gives the precursor 13. Reaction with methylidene-triphenylphosphorane and butyllithium generated 14 which reacted with benzil derivatives to give the pyrroles. 

A phosphine imine diazonium salt is formed when sodium azide is added to a solution of triphenylchlorophosphonium hexachloroantimonate in benzene (7.505). 

A commercially available polystyryldiphenylphosphine has been used to convert 3 -azido-3 -deoxy-nucleosides into the corresponding 3 -amino-3 deoxy-nucleosides, by formation and hydrolysis of phosphine imine intermediates. The formation of heterocyclic compounds on photolysis of glycosyl azides is covered in Section 6, and the formation of unsaturated sugars by radical elimination of vicinal phenyl selenide and xanthate azides from i ropriate saturated compounds is covered in Chapter 13. 

Azides, Diazoalkanes, Azo- and Azoxy-compounds, and Azines. Tiifluoro methyl azide, prepared from trifluoronitrosomethane, was shown previously to react in a conventional manner with triphenylphosphine to yield a phosphine imine ... 

If the Staudinger reaction of an alkyl azide containing a pendant carbonyl group is heated under anhydrous conditions, the iminophosphorane can nucleophilically attack the carbonyl leading to cyclic imines (via the aza-Wittig mechanism) and liberate phosphine oxide as shown below. The reaction also works intermolecularly. 

Phosphoranylideneaminoquinones, e.g. (20), have been prepared in good to excellent yields by the reaction of phosphines with [2,l]benzisoxazole-4,7-quinones, e.g. (19)." A safer alternative to the vinyl azide-based synthesis of (N-vinylimino)phosphoranes (21) has been reported (Scheme 1)." N-(AlkyIthiomethyl)iminophosphoranes (23) have been synthesised from the benzotriazole-substituted iminophosphorane (22) and used without isolation to provide routes to N-alkylthiomethyl-imines, -amides, and -ureas. Tetraazolyl-substituted ylides (25) and (26) are the products of the reaction of vinylphosphonium salts (24) with excess sodium azide." The novel 1,2-1 -azaphosphete (28), which is potentially antiaromatic, has been prepared by the reaction of the azide... 

Azides have been found to attack the phosphorus atom of 1,2,5-triphenylphosphole to give imino derivatives in a version of the well-known Staudinger reaction of phosphines <72CC1242>. Yields of the crystalline imines (see also Section 2.15.6.4) are in the range 40-95%. 

Tertiary phosphines react with chloramine to give amino-substituted phosphonium cations (6.104), and with azides either these phosphonium cations (6.105) or phosphonium imines can be obtained (6.106) (Chapter 7.10). 

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