Efficient Addition Reaction of Dibutylphosphane Oxide with Alkynes: New Mechanistic Proposal Involving a Duo of Palladium and Brønsted Acid
作者:Jun Kanada、Masato Tanaka
DOI:10.1002/adsc.201000758
日期:2011.4.18
The addition reaction of dibutylphosphane oxide [Bu2P(O)H] with alkynes proceeds efficiently in the presence of palladium‐chelating phosphane–Brønsted acid catalyst systems. Terminal alkynes afford branched‐structured products selectively. On the other hand, the same reaction using monodentate phosphane ligands or the reaction run in the absence of a Brønsted acid affords a much lower yield. A mechanistic
在存在钯螯合膦-布朗斯台德酸催化剂体系的情况下,二丁基氧化膦[Bu 2 P(O)H]与炔烃的加成反应有效地进行。末端炔烃选择性地提供分支结构的产品。另一方面,使用单齿膦配体的相同反应或在不存在布朗斯台德酸的情况下进行的反应收率要低得多。一种机械的研究显示,布朗斯台德酸(XOH)相互作用与以M氧 P(O)R 2种(M =钯,铂)通过氢键将它们转换成离子中号+ ←PR 2(OH⋅⋅⋅O - X)物种,这是由NMR光谱和X-射线晶体学确认。类膦PR 2(OH⋅⋅⋅O - X)部分具有不稳定的配位作用,这是通过与叔丁基异氰化物进行的配体交换反应证实的。已经提出了一种适应这些观察的新机制,以合理化由布朗斯台德酸诱导的催化活性和区域选择性的增强。