Phosphorazidic acid diphenyl ester

DIPHENYL PHOSPHORAZIDATE (Phosphorazidic acid, diphenyl ester)... 

Phosphonic acid, (phthalimidomethyl)-, diethyl ester, 65, 119 Phosphorazidic acid, diphenyl ester (26386-88-9), 68,1 Phosphoric triamide, hexamethyl- (680-31-9), 66, 51, 94 Phosphorodichloridic acid, 2-chloroethyl ester, 65, 68 Phosphorous acid, triethyl ester, 65, 108.119 Phosphorus oxychloride, 66,173, 176 67,1 68, 41,162 Phosphorus tribromide (7789-60-8), 67, 210 Phthalimide, N-(bromoethyl)-, 65, 119 Phthalimide, N-(hydroxymethyl)-, 65,119 Pig liver esterase, 69, 20... 

Diethyl phosphorocyanidate continues to be exploited for the purposes of conventional organic synthesis. Reported applications of the compound include a new conversion of carboxylic acids into esters or amides and also a ring-expansion reaction of 1,3-thiazoles in the penicillin series. Diphenyl phosphorazidate has been employed in a modified Curtius reaction/ in peptide synthesis, and for... 

The procedure described is essentially that of Shioiri and Yamada. Diphenyl phosphorazidate is a useful and versatile reagent in organic synthesis. It has been used for racemlzatlon-free peptide syntheses, thiol ester synthesis, a modified Curtius reaction, an esterification of a-substituted carboxylic acld, formation of diketoplperazines, alkyl azide synthesis, phosphorylation of alcohols and amines,and polymerization of amino acids and peptides. - Furthermore, diphenyl phosphorazidate acts as a nitrene source and as a 1,3-dipole.An example in the ring contraction of cyclic ketones to form cycloalkanecarboxylic acids is presented in the next procedure, this volume. 

Yokoyama, Y., Shioiri, T., and Yamada, S., Phosphorus in organic synthesis. Part 16. Diphenyl phosphorazidate (DPPA) and diethyl phosphorocyanidate (DEPC). Two new reagents for the preparation of thiol esters from carboxylic acids and thiols, Chem. Pharm. Bull., 25, 2423, 1977. 

A further example of the value of thioesters as acyl transfer agents is the production of esters from these reagents by reaction with an alcohol and N-bromosuccinimide. ° Both thio- and seleno-esters are readily available from free acids via the intermediacy of the acid imidazolide or 1,2,4-triazolide, which react smoothly with thiols or selenols to give the desired esters in high overall yields. Thioesters can also be prepared directly from free acids and thiols by condensation in the presence of either diphenyl phosphorazidate or diethyl phos-phorocyanidate. S-Ethylthioesters can be obtained, generally in high yields, by... 

Diphenyl phosphorazidate [DPPA, (Ph0)2P(0)N3l with 4-dimethylaminopyridine (DMAP) and lithium perchlorate opens epoxides regio- and stereo-selectively to yield O-diphenylphosphoryl vicinal azidohydrins see, for example, (15) (16). In the case of O, /3-epoxy ketones and esters, only the corresponding a-azidovinyl ketones and esters were obtained. This is attributed to the acidity of the a-H facilitating dephosphorylation of the initial product. 

Novel synthetic routes to thiol-esters use carboxylic acids and thiols with diethyl phosphorocyanidate or diphenyl phosphorazidate, and EtjN in DMF, ... 

General. Diphenyl phosphorazidate is a readily available, nonexplosive, and relatively stable azide widely used as a reagent in peptide synthesis, " and as a versatile reagent in a wide array of organic transformations. DPPA has been successfully utilized in the synthesis of a-amino acids and o-aryl carboxylic acids direct preparation of thiol esters from carboxylic acids and thiols the stereospecific preparation of alkyl azides and the phosphorylation of alcohols and amines The application of DPPA in a modified Curtius reaction permits a simple one-step conversion of carboxylic acids to urethanes under mild reaction conditions. DPPA acts as a nitrene source, and can undergo 1,3-dipolar cycloaddition reactions. The Curtius degradation of carboxylic acids in the presence of f-butanol gives the Boc-protected amine directly (eq 1). 

DPPA has been used for the direct C-acylation of methyl isocyanoacetate with carboxylic acids to give 4-methoxycarbonyloxazoles. t-Daunosamine, the glycone component of anticancer anthracycline antibiotics, has been synthesized from L-lactic acid in 9 steps with a 24% overall yield, where a key step in the sequence is the direct C-acylation of methyl isocyanoacetate with the lithium salt of the lactate ester using diphenyl phosphorazidate (eq 7). 

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