Transition states HERON reaction

Fig. 18 B3LYP/6-31G -derived energetics, ground and transition state properties for the HERON reaction of iV-methoxy-N-dimethylaminoformamide to 1,1-dimethyldiazene and methyl formate.

The formation of anhydrides 101 in the thermal decomposition reactions of TV-acyloxy-TV-alkoxyamides in non-polar mesitylene (Scheme 21, pathway (ii)) can thus be attributed to HERON migration of acyloxyl groups. However, the similarity of Eas for the two isomeric transition states raises the possibility that in these reactions some, or all of the ester might be generated by HERON migration of the alkoxyl substituent (Scheme 21, pathway (iii)). 

The reaction of azide with A-chlorohydroxamic esters has proved to be an excellent source of highly hindered esters . The rearrangement of 82 to 83 (Scheme 16), apart from being highly favourable energetically, is characterized by an early transition state with little disruption to the carbonyl. In these HERON reactions, the N—C 0) bond... 

FIGURE 26. B3LYP/6-31G transition state for the HERON reaction of //-formyloxy-At-(At, At -dimethylamino)formamide (214) to 1,1-dimethyldiazene (220) and methyl formate (173)... 

---