Collect. Czech. Chem. Commun. 2009, 74, 995-1009
Published online 2009-06-23 22:47:57

Preparation and structure of some sulfanylpropenylidene derivatives of Meldrum’s acid

Lynne A. Crawford and Hamish McNab*

School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK


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.

Keywords: Meldrum’s acid; Sulfanylpropenals; Push-pull conjugation; X-Ray diffraction; Dioxanes; Aldehydes; Knoevenagel condensations.

References: 24 live references.