Cyclic phosphorus compounds, reaction

It is well known that pentacovalent cyclic phosphorus compounds play an important role as intermediates in reactions involving nucleophilic attack on tetracoordinated phosphorus in biological systems. According to this background it appears to us that it is important to prepare the arsenic derivatives, which are more stable than the corresponding phosphorus compounds and allow the study of their conformation. 

Mann and his colleagues have employed the displacement reaction by Grignard reagents on phosphinous halides in the synthesis of cyclic phosphorus compounds 13 (136), 14 (7), and IS (7,83). Yields of the... 

Whilst the majority of the work described in this section involves the synthesis of cyclic phosphorus compounds, most of the chemistry could equally apply to arsenic and antimony and to a lesser extent bismuth. Most of the compounds synthesized have more than one heteroatom in the ring system, and not infrequently there are a number of heteroatoms, several of them often bound to the bridging metalloid atom, M. The methods most sucessfully applied to the synthesis of the parent and monoheterobicyclic compounds have been those involving addition and cycloaddition reactions. 

By application of the Corey-Winter reaction,vicinal diols 1 can be converted into olefins 3. The key step is the cleavage of cyclic thionocarbonates 2 (1,3-dioxolanyl-2-thiones) upon treatment with trivalent phosphorus compounds. The required cyclic thionocarbonate 2 can be prepared from a 1,2-diol 1 and thio-phosgene 4 in the presence of 4-dimethylaminopyridine (DMtVP) ... 

A common theme in the speculated polymerization reactions discussed in this section is that the polymers were generally uncharacterized or were composed of small cyclic oligomers. No evidence for high molecular weight polymers from low-coordinate phosphorus compounds was obtained. Of course, multiple bond formation, not polymerization, was the focus of these studies. 

A number of preparations of mixed halogenophosphoranes from tervalent phosphorus-fluorine compounds have been reported. For example, acyclic and cyclic fluorine compounds have been converted to phosphoranes, such as (36) and (37), by treatment with chlorine. Similar reactions leading to AA-dialkylaminodichlorodifluorophosphoranes (38) have been described and the stability of (38) to exchange processes commented upon. iVA-Dialkylaminotetraiodophosphoranes (39) have been prepared from AA-dialkylaminodichlorophosphines and lithium iodide, although no detailed physical evidence for the structure of these unusual compounds has yet been reported. The preparation of bis-(A-alkylamino)difluorophosphoranes (4) has been described above (see Section lA). 

The reason for this behavior in the case of the double-bonded structures ( A -type phosphorus) is the easy dimerization of the P=C bond. Tricoordinate planar (or nearly planar) phosphorus ( B - and C -type bonding) can be stabilized by repyramidalization when the cyclic electron delocalization is disturbed or lost (e.g., in a chemical reaction). The fine balance between these energetic effects cannot easily be predicted by using analogies or other simple models. Such predictions, however, can be made by using the sophisticated methods of computational chemistry, leaving the field of the chemistry of the aromatic phosphorus compounds an interesting research area with unexpected results in the future. 

A second type of five-membered cyclic oxyphosphorane is represented by derivatives of the 1,4,2-dioxaphospholane ring.111 These are made from the reaction of trivalent phosphorus compounds with certain aldehydes, for example 111... 

One method for the synthesis of cyclic silicon-phosphorus compounds is the reaction of alkaliphosphides with dichlorosilanes [1]. Using sodium/potassium phosphide, -arsenide, -antimonide and -bismutide Na3E/K3E (E = P, As, Sb and Bi) [2] with various di-, tri-, and tetrachloroorganosilanes, cages of the following types (Fig 1.) have been synthesized so far. 

If use is made of the five-membered cyclic phosphorus derivatives, the geometry of which is more suitable than that of the triphenylphosphine, formation of the phos-phorane intermediate is more favored and the yield of olefin increases. Deoxygenation with KSeCN in mildly alkaline medium can similarly occur by heteroatom exchange retention is observed as a consequence of double inversion. Open-chain compounds react with good yields, but cyclic oxiranes yields vary considerably with the number of ring atoms, due to steric hindrance. Alkali metal 0,0-diethyl-phosphorotellurates are very useful reagents for the conversion of terminal oxiranes, Eq. 104 but the reaction does work for other types. In the case of oxiranes formally derived from acyclic olefins, the (Z) compounds react more readily than the (E)-oxiranes. ... 

There have been a number of developments worthy of special mention in chemistry involving pentaco-ordinated compounds and intermediates. These include reports of molecular mechanics calculations to study the hydrolysis of cyclic phosphorus esters, further detailed studies of the reactions of tervalent phosphorus compounds with acetylene carboxylates and the first synthesis of a pentaco-ordinated phosphorus compound containing a three-membered (phosphirene) ring. There has also been further elegant work in the area of phosphatrane chemistry. 

In conclusion, we may expect further advances in understanding factors controlling structural and conformational preferences of cyclic oxyphosphoranes, both from an experimental as well as a theoretical point of view. As the area continues to develop, the use of oxyphosphoranes as models in mechanistic interpretation should enhance our understanding of pathways followed in nucleophilic displacement reactions of tetracoordinated phosphorus compounds. Acknowledgment... 

This paper describes the electrophilic ring-opening polymerization of seven new cyclic phosphorus(III) compounds, 1-7. The polymerization of five- and slx-membered deoxophostones, 1 and and of a benzoxaphosphole 2, produced poly (phosphine oxldejs 11, and via Arbuzov type reactions. The polymerization of f e and slx-" membered deoxothlolphostones, 4 and 5, gave poly(phosphine... 

Phosphorus-containing enamines have been prepared by phosphorylation of N-vinyl substituted tertiary amides, lactams and cyclic imides with phosphorus pentachloride ". Addition of amines to diphosphoryl alkynes has been described. Addition of RR NH [R = H, Ri = Me, cyclohexyl, PhCH2 RR = (CHj) to (Et0)2P(0)C=CP(0K0Et2)2 in CH2CI2 at 25 °C gave 93-100% of (Et0)2P(0)C(NRRi)=CHP(0)(0Et2)2 . Speziale and coworkers have studied the reactions of phosphorus compounds with trichloroacetamides. 

The only comprehensive and readily-available surveys of thio- and seleno-phosphonic and -phosphinic acids appear to be those in the compilation by Kosolapoff and Maier which appeared during the 1970s, and those in the Houben-Weyl volumes. Some further information relevant to heterocyclic systems which possess endo- or exo-cyclic phosphorus-sulphur bonds has been surveyed by Mann Gefter has also provided a useful compilation of syntheses and data for unsaturated thiophosphonates and related compounds. As in the preceding chapters concerned with the synthesis of the various classes of phosphonic and phosphinic acids, literature surveys have been presented for individual compounds and the field, as a whole, is surveyed annually". In addition. Hall and Inch reviewed the mechanistic implications of changes in stereochemistry following displacement reactions at phosphorus in cyclic phosphorus(V) esters and amides, and in so doing discussed the reaction s of many such thiophosphoryl compounds. 

A series of cyclic phosphoranes (86) has been obtained by the reaction of the bicyclic peroxide (84) with three-co-ordinate phosphorus compounds (85) and the products characterized by and n.m.r. The increasing ring... 

The organization of this Chapter has been changed somewhat from last year. Phosphonous and phosphinous acids and their derivatives, and cyclic esters of phosphorous acid, are not discussed separately from phosphorous acid and its derivatives, because of the similarity of the reactions involved. Two-co-ordinate phosphorus compounds are treated in a separate section like last year phospha-alkenes without phosphorus-heteroatom bonds are not covered. 

There follows a series of four papers by Houalla et al. on further extensions of the Atherton-Todd reaction to the synthesis of pentacoordinated phosphorus compounds with the phosphorus as a heteratom within a wide variety of macrocyclic structures. The first paper22 describes the reaction of 1-hydridobicyclophosphoranes containing a secondary amine group (e.g. 56) with (57) which leads to a cyclic / /s(bicyclophosphorane)-(58), as well as the symmetrical bicyclophosphorane (59). The opportunity to exploit the reaction in the synthesis of novel macrocyclic structures was too good to miss and compounds such as (62) were prepared from the corresponding 6/s-phosphorane (60) and the Ws-phenol (61).23... 

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