A bifunctional polystyrene bearing both DMAP and piperidine groups has been prepared and used as an organocatalyst for decarboxylative Doebner-Knoevenagel reactions of arylaldehydes and monoethyl malonate. Isolated yields of the resulting cinnamates were very high, and in all cases only the E-isomer was detected. When a polystyrene catalyst functionalized with only DMAP or piperidine groups was used in these reactions, catalysis was much less efficient. Furthermore, catalysis using a combination of the monofunctional polymers was also less efficient than with the bifunctional polystyrene. Thus, it appears that there is a synergistic effect obtained by co-locating the two different catalytic amine groups on the same polymer backbone.
一种双功能聚
苯乙烯被制备出来,具有
DMAP和
哌啶基团,并被用作芳醛和单
乙酯丙二酸的脱羧Doebner-Knoevenagel反应的有机催化剂。所得到的
肉桂酸酯的分离收率非常高,并且在所有情况下仅检测到E-异构体。当仅使用功能化为
DMAP或
哌啶基团的聚
苯乙烯催化剂进行这些反应时,催化效果明显不如双功能聚
苯乙烯。此外,使用单功能聚合物的组合进行催化的效率也低于双功能聚
苯乙烯。因此,似乎通过将两种不同的催化胺基团共同定位在同一聚合物主链上,可以获得协同效应。