Phosphorus, alkylation cyclic compounds

The five membered cydic 1,3-dioxolane (CHjOCHjCHjO) can be polymerised by a variety of catalysts including sulphuric acid (P7), perchloric acid (98), phosphorus pentachloride (PP) and alkyl aluminium compounds with water as a co-catalyst (100). The effect of the catalyst boron trifluoride diethyl etherate on the polymerisation of 1,3-dioxolane has also been studied and it has been found that equilibrium between monomeric 1,3-dioxolane and poly(l, 3-dioxolane) is set up in both the undiluted polymer and in solution (101-104). Controverf has arisen as to whether the equilibrium is between cyclic monomer and cyclic polymer (98) or between cyclic monomer and chain polymer (104). 

The Wittig reaction of phosphorus ylides derived from phosphonium salts with carbonyl compounds to form alkenes is widely used in synthetic chemistry. The alkylation of phosphorus ylides offers a route to a variety of phosphonium salts which can be further manipulated. Bestman and coworkers - have been responsible for a large number of reports based upon this and other aspects of phosphorus chemistry. Their work includes many examples of the intramolecular alkylation of ylides derived from phosphonium salts to form cyclic compounds. The salts can be prepared from dihalides either with triphenylphos-... 

Quite a number of cyclic phosphonium salts have been prepared over the years. We have not generally included compounds here which contain fewer than three potential binding sites in a ring unless they are mentioned as by-products in another reaction. Horner, Kunz and Walach have utilized the well-known alkylation approach to prepare cyclic phosphonium salts containing four phosphorus atoms. The formation of the cyclic tetraphosphonium salts is shown below in Eq. (6.14). 

Hydrazinopyridazines such as hydralazine have a venerable history as anti hypertensive agents. It is of note that this biological activity is maintained in the face of major modifications in the heterocyclic nucleus. The key intermediate keto ester in principle can be obtained by alkylation of the anion of pi peri done 44 with ethyl bromo-acetate. The cyclic acylhydrazone formed on reaction with hydrazine (46) is then oxidized to give the aromatized compound 47. The hydroxyl group is then transformed to chloro by treatment with phosphorus oxychloride (48). Displacement of halogen with hydrazine leads to the formation of endralazine (49). ... 

The reagent does not replace nitrogen atoms, and N-alkyl or N-aryl anthranilic acids yield 2,l-benzisothiazoline-3-thiones (94) on heating with phosphorus pentasulfide in xylene. Curiously, when alkyl iV-arylanthranilates are treated in the same way, only a very small proportion—less than 10%— of 94 is obtained. The major product (80%) is the cyclic phosphorus-containing compound (95), the identification of which gives some clue about the structures of possible intermediates.122... 

The situation is less clear-cut when the boron atom bears two alkyl groups as in compounds 40e and 40f.54,55 Although the NMR data at room temperature are found in the region of three-coordinate phosphorus and boron centers, low-temperature experiments showed a broadening of both the 31P and 11B signals, suggesting some P-B interaction. The X-ray diffraction analysis carried out on 40f54 did not reveal a cyclic structure... 

The complex of tartaric acid and antimony (emetic) was described three centuries ago. Nevertheless, the structure of this compound has been elucidated these last fifteen years by X-ray diffraction ( 1 ). In fact, emetic presents a binuclear cyclic structure. Many authors mentioned similar complex with transition metals (vanadium (2), chromium (3)) or metalloids (arsenic (4), bismuth (5)). Emetic with phosphorus was not mentioned. Nevertheless, tartaric acid or alkyl tartrates has been utilized in phosphorus chemistry tartaric acid reacts with trialkyl phosphites giving heterocyclic phosphites (6). Starting from alkyl tartrates, we prepared spirophosphoranes with a P-H bond and sixco-ordinated compounds (7). With unprotected tartaric acid, many possibilities appear condensation as a diol, as a di(oc-hydro-xyacid), or even as a 8-hydroxyacid. 

The nature of alkyl halide and the environment of the phosphorus atom make a substantial contribution to the direction of the reaction. Thus, cyclic phosphites [108], like trialkyl phosphites [110], react with preservation of the coordination of the P(III) phosphorus atom (126-132 ppm). If the alkoxyl group is substituted by amide, alkyl, or aryl, the nucleophilicity of the phosphorus atom in the corresponding amidophosphite (phosphonite) increases in comparison with the trialkyl phosphite. This probably promotes attack by 1 -haloalkyl-2-pyrrolidone at the phosphorus atom and not the oxygen, and this was confirmed experimentally. As a result of the investigated reactions amidophosphonates or ethyl phenyl phosphinates llOa-c were isolated compounds with P(III) were not detected in these cases. 

Cyclophosph(V)azanes with five-coordinate phosphorus are mostly dimeric, four-membered ring derivatives, [X3PNR]2 (6). Several reviews cover the subject. A simple preparation of these compounds involves the reaction of PCI5 with primary amines (or their hydrochlorides), the so-called Kirsanov reaction. Weakly basic amines form monomeric Cl3P=NR, but with more basic amines (e.g. with R = alkyl), the products are the cyclic dimers. Various anilines give either a monomer or a cychc dimer, depending upon their basicity. ... 

Carboalkoxy acyl halides are made from mono esters of dibasic acids and thionyl chloride or phosphorus pentachloride. Examples are numerous. Halides with the ester group in the beta position are unstable to prolonged heating. Alkyl halide is eliminated with the formation of an anhydride. Under certain conditions a rearrangement occurs in the preparation of ester acid chlorides. The product obtained is a mixture of the expected compound and its isomer in which the ester and acid chloride groups are interchanged, viz., ROjCCHR (CI ) CO,H — RO,C(CH,) CHR COQ. The cyclic anhydride is a likely intermediate. ... 

In principle, the reaction between a dihaloalkane (9) and a phosphorus(III) ester (10 (R = alkyl, aryl or alkoxy) initially affords the haloalkyl compound 11 the use of a trialkyl phosphite would thus lead to an (co-haloalkyl)phosphonic diester 11 (R = alkoxy, R = alkyl), whilst that of a phosphonite diester (10 R = alkyl, aryl) would afford an (co-haloalkyl)alkyl(or aryl)phosphinic ester. Depending on the ratio of reactants, further reaction might then take place (pathway A), resulting in the formation of the compounds 12. Depending also on n, and on the reaction temperature, the alternative pathway B may be followed the products are then cyclic phosphonic or phosphinic acid derivatives 13, and examples following both reaction pathways have been discussed (chapter 2, Section A). 

Ligands such as phosphines (PRj) and arsines (AsRs) (R = alkyl, aryl, halogen, etc.) form complexes with a variety of metals in various oxidation states. Vibrational spectroscopy has been used extensively to determine the structures of these compounds and to discuss the nature of the metal-phosphorus (M-P) bonding. Verkade reviewed spectroscopic studies of M-P bonding with emphasis on cyclic phosphine ligands. 

A detailed study of the desulphurization of the disulphides (301)(R,R = dialkoxy, or alkyl(alkoxy) ) by phosphorus(III) compounds, including (Mc2N)2P, Ph P, or acyclic or cyclic (based on catechol) phosphotriesters or ester amides) considered the role of phosphonium and phosphorane intermediates. The isomerization of (302) into (303), and the decomposition (desulphurization, deoxygenation, or dealkylation) into end products, are influenced by electronic and steric factors. 

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