Azides by the Mitsunobu Reaction

The explosive hydrogen azide can be replaced by less dangerous diphenylphosphoryl azide (DPPA). In the presence of this reagent, triphenylphosphane and diisopropyl azodicarboxylate (DIAD) the anti homoaUylic alcohol 151 is converted into the syn azide 

152 in 95% yield. Also using DPPA, a one step synthesis of A/-Boc-c -4-azido-L-proline methyl ester (154) has been reported using protected tran5-4-hydroxyl-L-proline 

Thompson et al. reported that the conversion of alcohols to the corresponding azides with inversion of configuration could be achieved using DPPA and DBU, where DBU acts as a base in the conversion of the alcohol into the corresponding phosphate interme- 

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Organic Azides Syntheses and Applications 3.2.3 Azides by the Mitsunobu Reaction... 

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