Diphenylphosphoryl azide, activation

Carboxylic acids can also be activated by formation of mixed anhydrides with various phosphoric acid derivatives. Diphenylphosphoryl azide, for example, is an effective... 

Macrocyclic lactams.1 These lactams have generally been prepared by reaction of dicarboxylic acid chlorides and diamines under high dilution. Yields are generally mediocre because linear polyamides are also formed. Actually, free dicarboxylic acids, when activated by diphenylphosphoryl azide, can condense with diamines to... 

Yamada s coupling reagent (diethylcyanophosphonate, DEPC) is representative of phosphorous based activators, including diphenylphosphoryl azide. 

Diphenylphosphoryl azide (DPPA) has also been used as an activating agent for the ring closure of dicarboxylic acids with polyamines to give high yields of the cyclic bis-amides (Qian et al., 1990). Cryptands have also been... 

Three new synthetic methods for the conversion of alcohols into azides (and hence potentially into amines) have been published. One route involves a further application of the chemistry of 2-alkoxypyridinium salts (formed in situ from an alcohol and the 2-fluoropyridinium salt) in their reaction with azide ion " (Scheme 17). Another extends the utility of the triphenylphosphine-ethyl diazodicarboxylate system, using diphenylphosphoryl azide as azide donor (Scheme 18), but is sensitive to steric hindrance at the alcohol carbon. The third route (Scheme 19) achieves oxygen activation through the alkoxyphosphonium salts (39), which are prepared from the alcohol, a phosphine, and a positive halogen donor such as carbon tetrachloride (with primary alcohols) or Af-chlorodi-isopropylamine (in... 

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