The iminoborane tBuB≡NtBu as a dipolarphile in (2+3) cycloadditions

Article abstract of DOI:10.1002/zaac.200500010

The iminoborane tBuB≡NtBu and the diazomethane tBuCH=N₂ give the (2+3) cycloadduct [-HC(tBu)-N=N-N(tBu)=B(tBu)-] in a 1:1 reaction and the seven-membered ring [-C(tBu)=N-NH-N(tBu)=B(tBu)-N(tBu)=B(tBu)-] in a 2:1 reaction. The (2+3) cycloadduct decomposes above 0°C to give the seven-membered ring, N₂, and HC(tBu)=N-N=CH(tBu) in the ratio 2:1:1. The borane tBuB≡NtBu and organic azides R″N₃ yield the (2+3) cycloadducts [-R″N-N=N-N(tBu)=B(tBu)-] (R″ = Me, Et, Pr, Bu, iBu, sBu, C₅H₁₁, c-C₅H₉, c-C ₆H₁₁, Bz1, EtOOC).