The impact of Lewis acid variation on reactions with di- tert -butyl diazo diesters.

Reactions of ( t BuO 2 CN) 2 with Lewis acids and FLPs have previously been shown to prompt the formation of diazene compounds. In this work, we show that the reaction of ( t BuO 2 CN) 2 with 9-BBN leads to a bicyclic heterocyclic product ( t BuOCO(BBN)CN) 2 1. In contrast, the reactions of ( t BuO 2 CN) 2 with BF 3 or [Et 3 Si][B(C 6 F 5 ) 4 ] lead to the isolation of [ t BuNHNH 2 t Bu][BF 4 ] 2 and [ t BuN(H)N t Bu][B(C 6 F 5 ) 4 ] 3, respectively. The mechanism for the formation of 2 is probed computationally, demonstrating that steric and electronic considerations of the Lewis acid impact the reaction pathway.