10.1021/jo981457i.s002 William H. Pearson William H. Pearson Erland P. Stevens Erland P. Stevens Cycloaddition of Heteroatom-Substituted 2-Azaallyl Anions with Alkenes. Synthesis of 1-Pyrrolines and Bridged Azabicyclic Compounds American Chemical Society 1998 alkene CHNC anion pyrroline NR 2 R 1 R 2 stannyl imidates heteroatom substituents cycloaddition CH reaction conditions alkyl groups alkyl halides methoxy carbonyl compounds azaallyl 1998-11-25 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Cycloaddition_of_Heteroatom-Substituted_2-Azaallyl_Anions_with_Alkenes_Synthesis_of_1-Pyrrolines_and_Bridged_Azabicyclic_Compounds/3715461 Nonstabilized 2-azaallyl anions bearing heteroatom substituents [R<sup>1</sup>CHNC(X)R<sup>2</sup>(−)Li(+), where R<sup>1</sup> and R<sup>2</sup> are hydrogen or alkyl groups and X = OMe, SPh, or NR<sub>2</sub>] were generated and found to undergo efficient [3 + 2] cycloadditions with alkenes to provide 1-pyrrolines after loss of LiX. The 2-azaallyl anions were generated by tin−lithium exchange on stannyl imidates, thioimidates, or amidines R<sup>1</sup>CH(SnBu<sub>3</sub>)NC(X)R<sup>2</sup> with <i>n</i>-butyllithium. The initially formed 1-pyrrolines were found to be deprotonated under the reaction conditions to afford 1-metalloenamines, which could be quenched with alkyl halides, carbonyl compounds, or MeSSMe to provide further functionalized 1-pyrrolines. Cyclic methoxy-substituted 2-azaallyl anions were generated and were found to undergo cycloadditions with alkenes to afford bridged azabicyclic compounds (1-methoxy-7-azabicyclo[2.2.1]heptanes and 1-methoxy-8-azabicyclo[3.2.1]octanes). These are the first examples of cyclic nonstabilized 2-azaallyl anions.