Spirocyclic phosphorus derivatives

As far as the reaction mechanism is concerned, we assume that the sequence conunences with the addition of the Lewis add to the carbon atom of the phosphaalkyne (9 - 69), in accord with the polarization of the PsC bond [10b]. The addition of fluorosulfonic acid to 9 a in liquid SO2 also begins with C-protonation [63]. The resultant, activated phosphaal-kenes undergo [2 -1- 2]-cycloaddition with a second equivalent of 9 to furnish the adducts 70. A subsequent [2 -I-1]-cycloaddition with a third equivalent of 9 is then responsible for the formation of the spirocyclic phosphorus derivatives (- 71). 

Japanese workers reported in 1956 (J. Pharm. Soc. Jpn., 76, 966 (1956)) that phosphorus trichloride-catalysed cyclisation of A-(3,4-dimethoxyphenylacetyl)tryptamine in boiling benzene gave the expected dihydro-p-carboline derivative. A recent reinvestigation of this reaction, however, showed that the major product, formed in 46% yield, is in fact the spirocyclic indoline derivative 1. When TFAA in benzene was used for the cyclisation, the indoline 2 was obtained in quantitative yield. 

There are many cyclic compounds known containing P and Si atoms in the ring but the majority have organic substituents on the silicon. (Details of the structures of such compounds are available.An exception is the spirocyclic compound (19), formed using an alkali metal-phosphorus derivative (equation 34). ... 

P-spirocyclic ferrocenyl derivatives [NP0CH2P(S)RCH20][NC(NR 2)2]2 (R =. CH2C5H4FeC5H5) have been synthesised from [NPCl2][NC(NR 2)2]2 by a nucleophilic substitution at the phosphorus centre. 

The difunctionality of NH2 moiety in the methylhydrazine derivatives has also been underlined by the reaction of (156) with trimethylorthobenzoate to afford the l-phospha-2,3,5,6-tetrazine derivative (163), which on oxidation with benzoquinone can be transformed to the radical species (164). EPR and ENDOR spectroscopic experiments clearly point to a spin polarization through the spirocyclic phosphorus atom to the other phosphorus and nitrogen nuclei in the phosphazene ring of (164). ... 

The only structurally characterized derivative of a trisimido organophos-phonate anion is the spirocyclic tellurium(IV) complex (19), which is obtained from the interesting redox reaction between PhPCl2 and [Li2Te(N Bu)3 ] 2 [27]. The phosphorus(V)-centered ligands are generated by imide transfer from tellurium to the phosphorus(III) atoms with concomitant reduction of one-half of the tellurium in the Te(IV) reagent to elemental tellurium [27]. 

Several examples of direct ring phosphorus interaction with transition metals are now known [279-287]. For example, reaction of N3P3CI6 with Na2Fe2(CO)g affords a novel spirocyclic diiron octa carbonyl derivative (Scheme 25) [282, 283]. The diiron spiro derivative acts as a template for the construction of several transition metal clusters. Some of the other examples where ring phosphorus atom is involved in interaction with transition metals are summarized in Scheme 25. The ring phosphorus atoms in hydrido phos-phazenes, N3P3R4R H also coordinates to transition metals. This has been discussed in an earlier section (vide supra). 

Under UV radiation, the phosphorane azide 28, which is one of the first thermally stable derivatives in which A5-phosphorus is bonded to five nitrogen atoms, is quantitatively converted into the new spirocycle phosphorane 29 (equation 13)66. 

Interest in hypervalent phosphorus chemistry has been maintained especially with regard to structural studies and the synthetic utility of pentaco-ordinate phosphorus compounds. Conformational effects of ring fusion and heteroatom substitution in six-membered rings of spirocyclic oxyphosphoranes have received further attention and hence added fuel to the debate over the occurence of diequatorial six-membered ring orientations as tbp models for enzymatic action on c-AMP. Finally, a novel departure has occurred in the area of hexaco-ordinate phosphorus chemistry with the preparation of further derivatives of the porphyrin ring system containing hypervalent phosphoras coordinated by the tetnqiyrrole unit... 

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