Gold Catalysis: Alkylideneoxazolines and -oxazoles from Intramolecular Hydroamination of an Alkyne by a Trichloroacetimidate
作者:A. Stephen K. Hashmi、Matthias Rudolph、Stefan Schymura、Jorge Visus、Wolfgang Frey
DOI:10.1002/ejoc.200600572
日期:2006.11
be prevented which delivered the oxazoles after long reaction times. Up to 3333 turnovers could be reached. With gold(I) catalysts in chloroform or dichloromethane selective hydroamination to 4-methylene-4,5-dihydrooxazoles without subsequent aromatization was exclusively observed. The gold(I) catalysts also allowed chemoselective cycloisomerization of N-propargylcarboxamides to 5-methylene-4,5-dihydrooxazoles
已经制备了几种炔丙基三氯乙酰亚胺并研究了它们与金催化剂的反应。只有炔丙基和 1-甲基炔丙基取代基才能观察到选择性环化;在乙腈中使用氯化金 (III) 仅获得快速加氢胺化为 4-亚甲基-4,5-二氢恶唑的产物,在氯仿中无法阻止较慢的后续芳构化,这会在长时间反应后释放恶唑。最多可以达到 3333 次失误。仅观察到在氯仿或二氯甲烷中使用金 (I) 催化剂选择性加氢胺化为 4-亚甲基-4,5-二氢恶唑而没有随后的芳构化。金 (I) 催化剂还允许 N-炔丙基甲酰胺化学选择性环异构化为 5-亚甲基-4,5-二氢恶唑。(© Wiley-VCH Verlag GmbH & Co. KGaA,