A Highly Efficient Method for the Synthesis of Nitrogen-containing Materials Using Umpolung Addition to Electron-Deficient Imines

2011年度～2013年度科学研究費補助金(基盤研究(B))研究成果報告書α位に電子求引基を有するイミン誘導体の極性転換共役付加反応を含む異常付加を基盤としたタンデム反応等の各種多段階反応の探索と、ファインケミカルズの効率的合成への展開を行った。特にβ,γ-不飽和-α-イミノエステルに対し、極性転換共役付加反応および生成するジエノラートの反応を完全な位置選択性で進行させることができた。さらに、α位に電子求引基を有するα-アシロキシイミノエステルに対し、窒素原子上でのSN2型の求核置換反応を活用して窒素原子に二つの異なる置換基を導入し、イミニウム塩に変換した後に第三の求核剤と反応させ、一挙に三種類の置換基の導入が可能であることを明らかにした。We have already reported that the N-alkylation reaction of alpha-iminoester proceeds using aluminum reagents to give the N-alkylation products in high yields. In the present project, we investigated highly regioselective N-alkylation of beta, gamma-alkenyl-alpha-iminoesters and subsequent directed vinylogous aldol reaction with in situ generated dienolates. It was also found that the sulfenyl group of the alkene part improved the selectivity of both steps, leading to the formation of 3-amino-2-pyrones by anti-elimination of thiols. Furthermore, on treatment with two different Grignard reagents, alpha-acyloxyimino esters gave the corresponding dialkylation products with different substituents on the nitrogen atom. N,N,C-Trialkylated products with all different substituents were obtained via the oxidation and the nucleophilic addition reaction to the resulting iminium salts