Byproducts from the Cycloaddition

Azines, derived from two moles of diazoalkane with loss of nitrogen, have been observed as byproducts by several authors.11,53,71 

The isolation of 1H- and 4//-pyrazoIes from thermally induced sigma-tropic rearrangements of initially formed 3//-pyrazoles is discussed in Section IV.A.l. 

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