Phosphoramidic dichloride, dimethyl

PHENYL-l-PENTANOL, 61, 42 (+)-(/ )-l-PHENYI -1-PENTANOL, 61, 42 (S)-1-PHENYL-l-PENTANOL, 61, 42 N-Phenylpyrrolidinone, 60, 68 Phosphoramidic dichloride, dimethyl- [677-... 

Thioesters, Selenoesters, and Thioamides.—Commercially available phenyl dichlorophosphate has been reported to be a superior reagent to MV-dimethyl-phosphoramidic dichloride (4, 244) for the preparation of thioesters directly from carboxylic acids and thiols. Carboxylic acid chlorides can be efficiently converted into thioesters by reaction with adducts formed between thiols and l-methylpyridine-3,5-dicarboxylates. Alternatively, copper(i) mercaptides, formed from thiols and CuaO, or thallous thiophenoxide can be used. The latter method can also be used to prepare selenoesters as well as a-phenylthio-and a-phenylseleno-acids and esters from a-halo-acids and a-halo-esters, respectively. 

Solutions of tris(acetylacetonato)zirconium chloride, bis(acetylacetonato)zir-conium dichloride, tetrakis(acetylacetonato)zirconium, zirconium tetraacetate, or zirconium tetranitrate, all reduced with triethylaluminum in hexamethyl-phosphoramide, are said to lead to high molecular weight products [41]. Unfortunately, the solvent is no longer available because of its carcinogenicity. Perhaps such alternate solvents as formamide, dimethylformamide, dimethyl-sulfoxide, and acetonitrile should be investigated. 

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