Outlaw Victor K, d'Andrea Felipe B, Townsend Craig A
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States.
Org Lett. 2015 Apr 17;17(8):1822-5. doi: 10.1021/ol5036936. Epub 2015 Mar 27.
An efficient route to substituted N-fused aromatic heterocycles, including indolizines, imidazo[1,2-a]pyridines, and imidazo[1,5-a]pyridines from azole aldehydes, is reported. Wittig olefination of the aldehydes with fumaronitrile and triethylphosphine affords predominantly E-alkenes that undergo rapid cyclization upon treatment with a mild base. Substituent control of the 1-, 2-, and 3-positions of the resulting heteroaromatic bicycles is shown. Alternatively, the isolable E-alkene undergoes selective alkylation with electrophiles, followed by in situ annulation to indolizines additionally substituted at the 6-position.
报道了一种从唑醛合成取代的 N-稠合芳香杂环化合物（包括中氮茚、咪唑并[1,2-a]吡啶和咪唑并[1,5-a]吡啶）的有效方法。醛与富马腈和三乙膦进行 Wittig 烯化反应，主要生成 E-烯烃，该烯烃在用温和碱处理时会迅速环化。展示了对所得杂芳族双环 1-、2-和 3-位的取代基控制。另外，可分离的 E-烯烃与亲电试剂进行选择性烷基化反应，然后原位环合生成在 6-位额外被取代的中氮茚。
