Palladium-Catalyzed Heteroannulation of 1,3-Dienes To Form α-Alkylidene-γ-butyrolactones
作者:Steve V. Gagnier、Richard C. Larock
DOI:10.1021/jo991692g
日期:2000.3.1
by the palladium-catalyzed heteroannulation of a variety of 1,3-dienes by alpha-iodo and alpha-bromo acrylic acids. The best results are obtained by employing a catalytic amount of the sterically hindered chelating alkyl phosphine D-t-BPF [(di-tert-butylphosphino)ferrocene]. In most cases, this process is highly regioselective. The reaction is believed to proceed via (1) oxidative addition of the vinylic
α-亚炔基-γ-丁内酯很容易通过α-碘和α-溴丙烯酸的钯催化多种1,3-二烯的杂环化反应制得。通过使用催化量的空间受阻的螯合烷基膦Dt-BPF [(二叔丁基膦基)二茂铁]可获得最佳结果。在大多数情况下,该过程是高度区域选择性的。据信该反应是通过(1)将乙烯基卤化物氧化加成到Pd(0)上,(2)将有机钯加成到1,3-二烯的受阻较小的末端而形成pi-烯丙基钯中间体,和(3) )通过羧酸根离子对钯的亲核取代