BF3·OEt2-AgSCF3 Mediated Trifluoromethylthiolation/Cascade Cyclization of Propynols: Synthesis of 4-((Trifluoromethyl)thio)-2H-chromene and 4-((Trifluoromethyl)thio)-1,2-dihydroquinoline Derivatives

A BF3·OEt2-AgSCF3 mediated direct trifluoromethylthiolation/cascade cyclization of propynols involving the SCF3 anion nucleophilic pathway is developed. This protocol also provides an opportunity to construct valuable trifluoromethylthio-substituted 2H-chromene and 1,2-dihydroquinoline systems with high efficiency under mild conditions. Additionally, the developed BF3·OEt2-AgSCF3 reaction system could be scaled up to gram quantities in a satisfactory yield without inert gas protection.