Cyclic chlorophosphites

The reaction between the cyclic orthoester 8 and diethyl chlorophosphite 9 leads via transesterification to the two acetals 4 and 5, which cannot be separated by distillation. 

Scheme 4 Synthesis of l,3 5,6-bis-0-(chlorophosphite) 9, bis-amidophosphites 10, and P-diastereomers of cyclic thiophosphate 11...

A similar reaction sequence, which begins with the trisphosphitylation of mannitol (12) afforded three P-diastereomers of cyclic trithiophosphate 13 via the corresponding tricoordinated tris-chlorophosphite and amidophosphite (Scheme 5) [20],... 

Example 63 Meier in his studies on potential prodrugs derived from biologically active nucleoside monophosphates used the cyclic chlorophosphites 2-chloro-4-ff-l,3,2,-benzodioxa-phosphinines for the synthesis of the cyclic phosphotriesters having two ligands of different hydrolytic stability benzy-loxy and aryloxy [102]. 

Although carbazole itself will not react with diethylphosphoryl chloride, its potassium salt yields 76. ° The cyclic chlorophosphites 77 (R = H and Me) reacted without prior conversion of carbazole to its salt, giving 78 (R = H and Me). ... 

Cyclic chlorophosphite 69 was obtained in the reaction of 68 with PC13 under conditions elaborated by Lucas et al.57). Hydrolysis of 69 with less than stoichiometric amounts of water produced the required five-membered cyclic phosphite 70, being stable at least for a few days. The monosubstituted five-membered cyclic phosphites are known to undergo spontaneous polymerization when prepared by hydrolysis with a stoichiometric amount of water in the presence of tertiary amines used for HC1 traping S8,59). 

A special place in the series of phosphorylation reactions of pyrroles is occupied by the syntheses of phospholane structures containing pyrrole ring as substituent at the phosphorus atom. These compounds, obtained from potassiopyrrole and cyclic chlorophosphites, are convenient subjects for the study of transamidation, alcoholysis, etc. [24]. 

Additional examples of spirophosphoranes derived from amidrazones have been described. Unstable phosphoranes, e.g. (61), were obtained from cyclic chlorophosphites and o-phenylenediamine. They polymerized rapidly at... 

The chlorophosphonium complexes 39, produced (Scheme 8) during the synthesis of cyclic esters of arylphosphonic acids from aryldiazonium tetrafluoroborates and cyclic chlorophosphites, are decomposed by H2S to give the analogous esters of arylthiophos-phonic acids ... 

The hydrolysis of cyclic chlorophosphites [18-24], obtained by reacting phosphoms trichloride and diols, is one of the best methods for the preparation of cyclic H-phospho-nates (see Appendix). 

Second stage A mixture of water (3.6 g, 0.2 mol), triethylamine (20.2 g, 0.2 mol), and tetrahydrofuran (10 ml) was added dropwise, with efficient stirring and cooling to a solution of cyclic chlorophosphite (0.2 mol) in benzene (250 ml) at 0-5 C. The mixture was kept for 1 h at room temperature and then filtered. The triethylamine hydrochloride was washed with benzene (2 times 100 ml). The solvent was removed under reduced pressure and the residue distilled to give the corresponding cyclic H-phosphonate. 

Nevertheless, most of the work reported on the post-polymerization modification of poly(all lene H-phosphonate)s concerns the functionalization with reactive pendant groups that include hydroxyl or amino groups, which make possible the introduction of a wide range of (bio)ac-tive molecules and leading to new reactive PPEs with tunable properties for biomedical applications. Most of the post-polymerization functionalization methods involve the corresponding polymeric chlorophosphite, since it was early demonstrated that cyclic allgrlene chlorophosphites such as 2-chloro-2-oxo-l,3,2-dioxaphospholane cannot be polymerized efficiently. ... 

L-Ascorbic acid has been converted to the cyclic alkylenephosphites 49 by reaction with alkylene chlorophosphites, and to the 2, 3 -cyclic phosphites 50 by treatment with phosphinidyne triimidazole followed by isopropylideneglycerol. Compounds 49 and 50 were treated with sulfur or selenium to give the corresponding thio- or seleno-phosphates. The 2-phosphate 51 of 5,6-0-isopropylidene-D-eo t ro-ascorbic acid was prepared by use of POCI3 under basic conditions. As minor by-products, the 2-diphosphate and the 2,2 -phosphodiester were formed. ... 

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