Cycloadditions of 2-Azaallyllithium Species with Conjugated Polyenes

2-Azaallyllithium species [R1CH(−)NC(X)R2Li(+), where R1 and R2 are alkyl and X = OMe] were generated by tin−lithium exchange of (2-azaallyl)stannanes and underwent [π4s+π2s] and [π6s+π4s] cycloadditions with cyclic dienes and trienes, respectively, to generate novel bridged azabicyclic compounds in a highly diastereoselective endo fashion. The periselectivity using cycloheptatriene was modest, producing a 1:1 mixture of [π6s+π4s] and [π4s+π2s] adducts. The reactions of 2-azaallyllithium species with dienes proceeded by a [π4s+π2s] pathway. The cycloadducts derived from cyclic 2-azaallyllithium species possess the 7-azabicyclo[2.2.1]heptane (tropane) or 8-azabicyclo[3.2.1]octane ring system and have been elaborated into cocaine-like analogues.