Allylmetallation of 1-silylalkynes by 2-(bromozincmethyl)-2-alkenyl ethers followed by Pd(0)-catalyzed cyclization: A one-pot synthesis of 4-methylenecyclopentenes
作者:Jaap van der Louw、Juul L. van der Baan、Franciscus J.J. de Kanter、Friedrich Bickelhaupt、Gerhard W. Klumpp
DOI:10.1016/s0040-4020(01)89857-4
日期:1992.1
Reaction of 2-(bromozincmethyl)-2-alkenyl ethers 1a,b,c,d with 1-(trimethylsilyl)-1-alkynes 2 afforded carbometallation products 3, which were converted by Pd(0)-catalyzed cyclization to 4-methylenecyclopentenes 5. The rates of both the addition and cyclization step depend on the concentration of the organozinc compound and the preparation of 5 is best performed using a 1.4–1.8 M solution of 1. At
2-(溴锌甲基)-2-烯基醚1a,b,c,d与1-(三甲基甲硅烷基)-1-炔烃2的反应得到碳金属化产物3,其通过Pd(0)催化的环化反应转化为4-亚甲基环戊烯5。加成和环化步骤的速率均取决于有机锌化合物的浓度,最好使用1.4–1.8 M的1溶液进行5的制备。在较低浓度下,反应时间必须更长,并且当1c反应时,添加不完全,会产生混合产物(3和14)。),在Pd(0)处理后会生成异构体亚甲基环戊烯(5、15和16)的混合物。