5-(Methylthio)tetrazoles as versatile synthons in the stereoselective synthesis of polycyclic pyrazolines via photoinduced intramolecular nitrile imine–alkene 1,3-dipolar cycloaddition
作者:Daniel Pla、Derek S. Tan、David Y. Gin
DOI:10.1039/c4sc00107a
日期:——
A key thioether substituent in readily accessible 2-alkyl-5-(methylthio)tetrazoles enables facile photoinduced denitrogenation and intramolecular nitrile imine 1,3-dipolar cycloaddition to afford a wide range of polycyclic pyrazoline products with excellent diastereoselectivity. The methylthio group red-shifts the UV absorbance of the tetrazole, obviating the requirement in all previous substrate systems
易于获得的 2-烷基-5-(甲硫基)四唑中的一个关键硫醚取代基能够轻松进行光诱导脱氮和分子内腈亚胺 1,3-偶极环加成反应,从而提供多种具有优异非对映选择性的多环吡唑啉产物。甲硫基使四唑的紫外吸光度发生红移,避免了之前所有底物系统对至少一个芳基取代基的要求,并且随后可以转化为各种其他官能团。该合成平台已应用于生物碱天然产物(±)-newbouldine和withasomnine的简明全合成。