Isomerizable (E/Z)-alkynyl-O-methyl oximes employing TMSCl–NCS in chlorinative cyclization for the direct synthesis of 4-chloroisoxazoles
作者:Wilailak Kaewsri、Charnsak Thongsornkleeb、Jumreang Tummatorn、Somsak Ruchirawat
DOI:10.1039/c6ra09396e
日期:——
synthesized in moderate to excellent yields from (E/Z)-alkynyl-O-methyl oximes via chlorinative cyclization. The synthesis employs the combination of N-chlorosuccinimide (NCS) and chlorotrimethylsilane (TMSCl) in nitromethane solvent where chlorine (Cl2) and hydrochloric acid (HCl) are generated in situ. In addition, the current protocol is applicable to the synthesis of 4-bromo- and 4-iodoisoxazoles when
第一次,通过氯化环化反应,由(E / Z)-炔基-O-甲基肟直接以中等至优异的产率直接合成了4-氯异恶唑。该合成方法是在硝基甲烷溶剂中结合使用N-氯代琥珀酰亚胺(NCS)和三甲基氯硅烷(TMSCl),在其中原位生成氯(Cl 2)和盐酸(HCl)。此外,当N-溴代琥珀酰亚胺(NBS)和N分别使用-碘代琥珀酰亚胺(NIS)代替NCS。从制备炔基-O-甲基肟的步骤开始,由于(E)-异构体可在该条件下异构化和环化,因此本方法可提高制备4-卤代恶唑的总效率。