Ring-Bond-Redistribution Graphs

Although for more detailed information it is necessary to consult the original articles, in principle the RBR graph of a reaction consists of a set of solid, dashed, and bold lines, in which the solid lines represent the bonds that are involved in the redistribution process but are not broken, the dashed lines represent the bonds that are broken or formed during the rearrangement, and the bold lines represent the chain of atoms that are unchanged during the conversion and are thus common in both initial and final product. 

To illustrate the principle of the construction of or RBR graph, a few examples are chosen from the different categories of degenearate ring transformations, as classified in Section LB. 

Sn(ANRORC) Reactions in Azines, Containing an Outside Leaving Group 

Amination of 2-chloro-, 2-bromo-, and 2-iodopyridine with potassium amide in liquid ammonia gave exclusively 2-aminopyridine. In this case an Addition-Mimination mechanism (Sn(AE) mechanism) has been proposed. The intermediacy of 2,3-pyridyne was considered to be highly unlikely (65AHC121). 

Similar experiments were carried out with 6-bromo-5-deuterio-4-phenylpyrimidine. When subjected to treatment of potassium amide/liquid ammonia, it was observed that the 6-aminopyrimidine did not contain deu- 

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