Phosphoranes imino

Phenylcyclopent[c]azcpine (33a) and 6,7-fused cyclopentazepines 33b-d are formed in moderate yields in a one-pot, two-stage process involving initial condensation of triphenyl-[(l-phenylvinyl)imino]phosphoranes 32 with 6-(dimethylamino)fulvene-2-carbaldehyde (30), followed by an intramolecular aza-Wittig reaction of the iminophosphorane with the pendant aldehyde function.5 The method fails with the unsubstituted vinylphosphorane 32 (R1 = R2 = H). 

Since the electrophilic character of carbonyl groups in acid halides is more pronounced than in carboxylic anhydrides, the former are better suited for aza-Wittig reactions. Zbiral et al. studied the reaction of imino-phosphoranes with acid halides and obtained imidoyl halides (69LA29 72PS35). A -alkyl and A -aryl iminophosphoranes can be set to use in this reaction (72PS35). 

The methods described here use oxiranes as reaction partners of imino-phosphoranes. The analogous electrophilicity of the oxiranes and the rather similar mechanism of an aza-Wittig-variant, however, justify their description within this section. Reaction of iminophosphorane 63 with phenoxymethyloxirane 64 (Scheme 36) leads at low temperature to 1,3,2-... 

In another approach, 2-(alkylamino)alcohol is employed as starting material for aziridine syntheses with the aid of dihalogenophosphoranes (70BCJ1185). Intramolecular transformation of 3-azidopropyloxirane 73 results in a simultaneous formation of a condensed aziridino[l,2-a]pyrrol-idine system (Scheme 39). The azide group is first transformed into imino-phosphorane 74, the nucleophilic N atom cleaves the oxirane to form betaine 75 [as in the Mitsunobu reaction (81S1)], and the phosphorus is shifted from N to O and then eliminated as phosphane oxide under simultaneous cyclization to bicyclic 76 (89JA7500). 

A recent review on four-membered heterocycles formed from imino-phosphoranes concentrates on the preparation and the reactivity of 2,4-diimino-l,3-diazetidine and related compounds (93JPR305). As an example, the synthesis via bisiminophosphorane 85 is described in Scheme 42. The bisiminophosphorane has both a heteroaryl and a styryl site. From a mechanistic view, the reaction of the bisiminophosphorane proceeds with aryl isocyanate formation via an aza-Wittig mechanism. Intermediate car-bodiimide formation (86) occurs directly on the iminophosphorane moiety... 

With the aid of a Knoevenagel condensation and a Staudinger reaction, 2-azidocyclopent-l-ene 1-carbaldehydes (195) can be converted into suitable products for a cyclopenta[b]pyridine synthesis [89JCS(P1)1369], as shown in Scheme 72. In order to bring the ester carbonyl function and the imino-phosphorane group into close proximity suitable for cyclization reactions, the 1,3-diene system 196 should possess the s-cis conformation. Furthermore, the exocyclic double bond should show a cis conformation. To achieve... 

IV. OTHER ORGANOLITHIUM COMPOUNDS A. Lithiation of Triphenyl((trimethylsilyl)imino)phosphorane, Ph3P=NSiMe3... 

The metathetical reaction of C02 with metal (Ti(IV), U(V)) arylimido-complexes led to an arylisocyanate and a metal-oxo species [4g, 115a]. In these processes, which take place under very mild conditions (ambient temperature and pressure), the metal center acts as the sink for unrequired oxygen. A common feature which characterizes these transformations from a mechanistic point of view is the intermediate formation of a metal carbimato-species through the [2+2] cycloaddition of C02 with the metal-imido complex (Scheme 6.23). By cycloreversion, the four-membered aza-metalla-cycle then converts into isocyanate and a stable metal-oxo complex. These processes, at least formally, are reminiscent of the reaction of imino-phosphoranes with C02 to give isocyanates and carbodiimides [115b,c]. 

The polymerisation of ethylene in the presence of an Ni(II) complex containing a ligand originating from aminobis(imino)phosphorane leads to short-chain branched polyethylene [182]. This is due to the copolymerisation of ethylene with short-chain 1-alkenes formed in such a system. 

Catalysts capable of 2, co-linkage of a-olefins are obtained from the reaction of Ni(0) or Ni(II) compounds, such as Ni(Cod)2 or Ni(All)2 respectively, with aminobis(imino)phosphorane, such as (Me3Si)2NP(=NSiMe3)2, preferably used in equimolar ratio the catalysts are characterised by the appearance of Ni(II) species as has been shown by scheme (18) [182]. 

Amino-bis-[imino]-phosphorane reagieren mit Diazomethan in Diethylether bei 0-5° unter Addition an eine P = N-Doppelhindung zu Phosphonsaure-diamid-imiden994 z. B. ... 

In the same manner 2-phenylthiazole and 2,3-substituted thiophene derived imino-phosphoranes react with one eqivalent of aryl isocyanate to give fused 1,3-diazepines in 50-72 % yield, while with two equivalents aryl isocyanate the [2-1-2] cycloadducts are obtained in 50-61% yield. ... 

Tandem nucleophilic/intramolecular addition also occurs in the reaction of the imino-phosphorane 32 (R = C02Me, CN) with isocyanates and nucleophiles (X = O, S, NR) to give 33. ... 

Also, p-phenylene diisocyanate 74 upon reaction of two equivalents of the imino-phosphorane 75 and subsequent refluxing in p-xylene, affords the bis-heterocycle 76 in 66%yield. ... 

Attempts to synthesize N-heterocyclic substituted carbodiimides from 1,2,4-triazine imino-phosphoranes 19 and isocyanates result in the isolation of the corresponding... 

Bis(imino)phosphoranes, R-P(=NR )2 of various types, methylene-iminophosphoranes, R-P(=CR2)(=NR0 as well as numerous iminooxo, iminothio, and iminoseleno derivatives, RP(Q)(=NR0 (Q = O, S, Se), are known and have been reviewed. 

The bis(imino)phosphoranes are prepared by a reaction sequence involving iminophosphine and cyclophosphate-trazenes, but readily dimerize to cychc four-coordinate compounds (diiminocyclodiphosphazanes) even with bulky organic substituents at nitrogen R = tert-Hu, CEts, 1-Ad (Scheme 12). ... 

Silylated bis(imino)phosphoranes, (Me3Si)2N P(=NSi Mes)2, can be prepared by a Staudinger reaction, from (Me3Si)2N P=NSiMe3 withMesSiNs. ... 

Hydrozirconation see Hydrozirconation) of phosphai-mines, phosphaalkenes, or bis(imino)phosphorane takes place with the formation of various three- or four-membered phosphazirconacycles. ... 

The aminobis(imino)phosphorane P[N(SiMe3)2](NSiMc3)2 undergoes cycloaddition with EX (=A1C13, SnCU, TiCU, NbClj, or FeCU) to yield X[(Mc3Si)2N]-... 

Further progress has been reported in the chemistry of CT X, -p -bonded systems. Full details of such systems stabilised by intramolecular coordination, as in, e.g., 334, have been described. The kinetically stable system 335 has been prepared and its solid state structure determined . The P-halobis(imino)-CT -phosphoranes 336 have also been prepared, and detailed NMR studies of bis(imino) phosphoranes reported . Quin s group has continued studies of the generation and characterisation of reactive a X -systems, e.g., 337 ". Methods for the generation of monomeric metaphosphate esters in solution have been investigated. A theoretical approach has been used to probe the mechanism of the reaction between phosphanylnitrenes 338 and boranes. The thiophosphonic anhydride 339 behaves as a source of the dithioxophosphorane... 

Recent examples of experimental and computational studies showing the involvement of hypercoordinate intermediates are cyclometallation of benzylamine with palladium acetate (91) and cyclopalladation of aryl imino-phosphoranes (92). ... 

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