Condensation of Meldrum’s acid with the 3-sulfanylpropenal derivatives 7a and 7b gives the 3-sulfanylpropenylidene derivatives 2a and 2b, respectively. NMR and X-ray analysis of 2a and 2b show that the electron-donating group conjugates with the electron-withdrawing dioxanedione moiety but the effect is much less pronounced than in analogous dialkylamino derivatives 1. There is little or no conjugation of the ortho-alkylsulfanyl group to the dioxanedione moiety in the benzylidene derivatives 4a and 4b.
Meldrum's酸与3-磺基丙烯醛衍生物7a和7b发生缩合反应,分别得到3-磺基丙烯基衍生物2a和2b。对2a和2b进行核磁共振和X射线分析表明,电子给体基团与电子受体二氧杂二酮基团共轭,但其效应比类似的二烷基胺衍生物1中的效应要弱得多。在苄亚甲基衍生物4a和4b中,磺基团与二氧杂二酮基团之间几乎没有或没有共轭作用。