Ruthenium-Catalyzed Cycloaddition between Propargylic Alcohols and Cyclic 1,3-Dicarbonyl Compounds via an Allenylidene Intermediate

Thiolate-bridged diruthenium complexes such as [Cp*RuCl(μ2-SR)2RuCp*Cl] (Cp* = η5-C5Me5; R
= Me, nPr, iPr) and [Cp*RuCl(μ2-SiPr)2RuCp*(OH2)]OTf (OTf = OSO2CF3) promote the cycloaddition
between propargylic alcohols and cyclic 1,3-dicarbonyl compounds to give either the corresponding
4,6,7,8-tetrahydrochromen-5-ones or 4H-cyclopenta[b]pyran-5-ones in high yields with complete
regioselectivity. This catalytic cycloaddition provides a simple and one-pot synthetic protocol for a
variety of substituted chromenones and cyclopenta[b]pyranones.

以硫醇盐桥联双核钌配合物（Thiolate-bridged diruthenium complexes）为例，如[Cp*RuCl(μ₂-SR)₂RuCp*Cl]（Cp* = η⁵-C₅Me₅；R为甲基、正丙基、异丙基）与[Cp*RuCl(μ₂-SPr)₂RuCp*(OH₂)]OTf（OTf = 三氟甲磺酰基，即OSO₂CF₃），可催化炔丙醇与环状1,3-二羰基化合物发生环加成反应，以高收率及完全区域选择性得到对应的4,6,7,8-四氢色烯-5-酮或4H-环戊并[b]吡喃-5-酮。该催化环加成反应为各类取代色烯酮及环戊并[b]吡喃酮提供了一种简便的一锅法合成策略。