Nickel(0)-Catalyzed Intramolecular [4 + 4] Cycloadditions: 5. The Type II Reaction in the Synthesis of Bicyclo[5.3.1]undecadienes
作者:Paul A. Wender、Mark J. Tebbe
DOI:10.1055/s-1991-28397
日期:——
The preparation and type II intramolecular [4 + 4] cycloaddition of a bis-diene is described in connection with studies on the synthesis of taxol (1), crispolide (2), and vulgarolide (3). The required bis-diene is prepared by a carboalumination of an alkyne, giving an iodide which is then coupled in the presence of palladium to a vinyltin to give a stereodefined diene. Elaboration of this system involves the reaction of 2-lithio-1, 3-butadiene with a dienal to give a bis-1,3-diene tethered at the terminus of one diene and the internal position of the other. Cycloaddition of this bis-diene mediated by a nickel(0)/tri-o-biphenyl phosphite catalyst provides a bicyclo[5.3.1]undecadiene, a ring system common to a variety of complex molecules.
本文描述了一种二烯的制备及其类型 II 分子内 [4 + 4] 环加成,涉及紫杉醇(1)、脆朊醇(2)和普通醇(3)的合成研究。所需的二烯通过炭铝合成法从炔烃制备,得到的碘化物随后在钯的存在下与乙烯锡偶联,形成立体定义的二烯。该体系的进一步转化涉及2-锂-1,3-丁二烯与一个二烯醛反应,生成一个双1,3-二烯,该双烯在一个二烯的末端和另一个的内部位置上连接。通过镍(0)/三-o-苯基磷酸盐催化剂催化的该双烯的环加成反应生成了一个双环[5.3.1]十一烯,这是一种在多种复杂分子中常见的环系。