Intermolecular Diels–Alder Cycloaddition/Cross-Coupling Sequences of 2-Bromo-1,3-butadienes
作者:Hans Choi、Harry J. Shirley、Harry R. M. Aitken、Tim Schulte、Tilo Söhnel、Paul A. Hume、Margaret A. Brimble、Daniel P. Furkert
DOI:10.1021/acs.orglett.9b04567
日期:2020.2.7
activated dienophiles proceeded under Lewis acid catalysis in generally high yields with good to excellent endo diastereoselectivity. The resulting vinyl bromide cycloadducts underwent subsequent Stille and Suzuki cross-couplings under standard conditions in good yields. Both the Diels-Alder and cross-coupling steps were highly tolerant of a range of functionalities and protecting groups. The use of the
已证明2-溴-1,3-丁二烯是串联Diels-Alder /过渡金属交叉偶联反应序列的有效底物。2-溴-1,3-二烯与活化的亲二烯体的分子间环加成反应在路易斯酸催化下以通常高收率进行,具有良好或优异的内非对映选择性。在标准条件下,将所得的乙烯基溴化物环加合物进行随后的Stille和Suzuki交叉偶联,收率良好。Diels-Alder和交叉偶联步骤均高度耐受一系列功能和保护基团。将溴取代基同时用作环加成引导基团和交叉偶联核试剂,可避免为每次转化安装和除去更常用的甲硅烷基烯醇醚和烯醇磺酸盐所需的额外步骤,并在整个反应序列中完全控制烯烃的区域化学反应。2-溴-1,3-二烯由三步法方便地从容易获得的醛制备,并确定为水解稳定和实用的合成中间体。