Phosphonic acid chlorides oxalyl chloride

Preparation of Phosphonic Acid Chlorides. Phosphonic acid dichlorides have been obtained in high yield (determined by NMR) at low temperature from the corresponding acids using oxalyl chloride and Pyridine (eq 1) ... 

Preparation of Phosphonic Acid Chlorides. Disilyl esters of phosphonic acids react with oxalyl chloride-DMF to give the phosphonyl chlorides and silyl chlorides under mild conditions (eq (>) Prior treatment of an acid-sensitive phosphonate monoester with Trimethylsilyldiethylamine was used to minimize exposure to HCl (eq 7). ... 

Synthesis of isomeric chiral protected (63 )-6-amino-hexahydro-2,7-dioxopyrazolo[l,2- ]pyrazole-l-carboxylic acid 280 is shown in Scheme 36. Crude vinyl phosphonate 275, obtained by treatment of diethyl allyloxycarbonylmethyl-phosphonate with acetic anhydride and tetramethyl diaminomethane as a formaldehyde equivalent, was used in the Michael addition to chiral 4-(f-butoxycarbonylamino)pyrazolidin-3-one 272. The Michael addition is run in dichloro-methane followed by addition of f-butyl oxalyl chloride and 2 equiv of Huning s base in the same pot to provide 276 in 58% yield. The allyl ester is deprotected using palladium catalysis to give the corresponding acid 277, which is... 

In case of carboxylic acid starting materials, they were first converted into their corresponding acyl chlorides by reacting with oxalyl chloride in dichloromethane. A cooled dichloro-methane solution of an acyl chloride (1 1 mmol) in a 25 mL round bottomed flask was then added with triethylphosphite (1 mmol) drop-wise under stirring, and the reaction mixture was allowed to attain room temperature. On completion of the formation of acyl phosphonate, the reaction mixture was reduced in vacuo, and benzoic acid (2 mmol) was added directly to the residue, followed by benzene. The mixture was stirred to dissolve completely, then hydrazine solution in THF (1.05 mmol) was added drop-wise under rapid stirring. On completion of hydrazone formation, the reaction was flash-frozen and lyophilized. After lyophilization, 1 1 v/v tetrahydrofuran ferf-butanol was added to the flask and stirred to dissolve the solid. Potassium ferf-butoxide solution (3 mmol) in 1 1 v/v tetrahydrofuran ferf-butanol was then added to the stirring solution in one portion. After stirring at room temperature for several hours, the reaction was diluted with ethyl acetate (50 mL), quenched with 1 N HCl (20 mL), washed with saturated sodium bicarbonate (2 x 15 mL), then with brine (15 mL),... 

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