Rearrangement Hoffmann

Carboxylic acid, 161, also serves as starting material for a substituted pyrazine that has proven to be an important diuretic agent. As the first step in the synthesis the acid is converted to the corresponding amide (165). Treatment with a single equivalent of hypobromous acid effects Hoffmann rearrangement of only one of the amide groups. Ethanolysis of the intermediate carbamate leads directly to the amino ester (166). Exposure of the... 

The oxidative method using C6H5l(OAc)2 3uelded the desired quadricyclyl azide and the process is being scaled up. In another approach (Fig. 2.17), the hypervalent iodine Hoffmann rearrangement was carried out on quadricyclyl carboxamides. 

Figure 2.17 Alternative approach with Hoffmann rearrangement...

Amino-5-cyanoimidazole can also be obtained nonphotochemically. The monocarboxamide from hydrolysis of 13 (R = H) (see Section IIl.B) undergoes Hoffmann rearrangement on treatment with chlorine and sodium hydroxide to give 8 (Scheme 2) (76JAP(K)51-1466, 1467, 1468). 

Another example is the Hoffmann rearrangement of alkylamino-benzenes to p-alkylanilipes ... 

Schmidt Reactions. This term is used for several transformations, general examples of which are shown in eqs 11 and 12. The former is used infrequently due to the drastic conditions required compared to the analogous Curtius and Hoffmann rearrangements and the discovery that DPPA effects the transformation under mild conditions. TMSN3 has been used frequently. 

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