With carbon-phosphorus bond, preparation

The present effort is intended to provide an update of the earlier edition, bringing to the chemist in concise form advances in the approaches to C-P bond formation previously discussed, as well as several other aspects of C-P bond formation. These latter aspects include the generation of organophosphorus compounds from elemental phosphorus (of particular industrial interest for purposes of cost containment) advances in the preparation of phosphoranes, including the use of transient oxophosphoranes as intermediates in organophosphorus compound syntheses and new approaches toward the preparation of compounds with aromatic and vinylic carbon-phosphorus bonds. 

In this chapter, we consider two aspects of carbon-phosphorus bond formation as they relate to pentacoordinated phosphorus species. The first aspect is the preparation of stable phosphorane species — compounds bearing five bonds to phosphorus with at least one of them being a C-P linkage. At present, this is an area of rather specialized interest, but one that has potential for broader applications. 

A palladium-assisted reaction has also been used in the preparation of vinylic carbon-phosphorus bonds by addition to terminal alkynes.81 This reaction (Figure 6.20) provides vinylicphosphonates in good yield with reasonable regioselectivity (9 1) favoring addition at the internal position of the terminal alkyne. 

Sugars containing a carbon-phosphorus bond have been prepared by application of the Michaelis-Arbuzov reaction to bromodeoxy sugars. Thus, the reaction of 5-bromo-5-deoxy-l,2-0-isopropylidene-3-O-methyl-a-D-xylofuranose (131) with triethyl phosphite yields the corresponding diethyl phosphonate (132) compound 132 was employed for the synthesis of a sugar derivative having phosphorus as... 

Hexacoordinated phosphorus species bearing a formal positive charge have been generated, albeit without a carbon-phosphorus bond. Rather, compounds of the type for which an example is shown as (16) have been prepared with four oxygen and two nitrogen ligands with an overall positive charge. ... 

Carbon-silicon bonds can be formed by treating the lithio intermediate with halogen-containing silanes (Reaction 22) (28). Carbon-phosphorus bonds can be prepared similarly (Reaction 23) (29). 

In complete analogy with procedures noted for the preparation of phosphines (see Section 3.2), carbon-phosphorus bonds may be generated directly from P(V) halide species using organometallic reagents (equation 35). 

Phosphorus-containing compounds provide useful substrates for ozonolysis reactions as well and can provide several products depending on the reaction workup. Several biological uses exist for -amino-a-hydroxy phosphonic acid derivatives and they can be readily prepared by ozonolysis of Al-(ethoxycarbonyl)-/3-amino-Q -methylene phosphonic esters after reductive workup with sodium borohydride (eq 54). When the reaction mixture is treated with sodium hydroxide in MeOH, an anomalous ozonolysis reaction occurs and cleavage of the methylene as well as the carbon-phosphorus bond occurs to yield (V-(ethoxycarbonyl)-a-amino methyl carboxylic esters. 

This review has shown that the analogy between P=C and C=C bonds can indeed be extended to polymer chemistry. Two of the most common uses for C=C bonds in polymer science have successfully been applied to P=C bonds. In particular, the addition polymerization of phosphaalkenes affords functional poly(methylenephosphine)s the first examples of macromolecules with alternating phosphorus and carbon atoms. The chemical functionality of the phosphine center may lead to applications in areas such as polymer-supported catalysis. In addition, the first n-conjugated phosphorus analogs of poly(p-phenylenevinylene) have been prepared. Comparison of the electronic properties of the polymers with molecular model compounds is consistent with some degree of n-conjugation in the polymer backbone. 

Carbon-phosphorus double bonds are also formed in addition reactions of tris(trimethylsilyl)phosphine 1692 (which can be readily prepared from white phosphorus, sodium, and TCS 14 [13a,b,c]) to give oxazohum fluorides 1691 which then give the azaphospholes 1694, via 1693 [3, 14]. On addition of 1692 to 1695, the diazaphosphole 1696 [3, 15] is prepared, whereas l,3-azaphospholo[l,2a]pyridines 1698 [16] are formed from 1692 and 1697, and 1,3-thiaphospholes 1700 are formed from the dithiohum fluorides 1699 [17]. l,3-Benzodiphospholyl anions 1703 are generated by reaction of acid chlorides with the dihthium salts 1701, via 1702 [18] (Scheme 11.3). 

Suppose the -1 ion containing one atom each of nitrogen, phosphorus, and carbon could be prepared. Describe the structure of this ion in some detail with regard to the type of bonding and resonance. 

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