[jp81024]

 Trying to get this Knoevenagel condensation (substituted pyran deriv. with benzaldehyde) reaction to work have tried numerous attempts with different equivelents of everything.  Have mainly tried in propanol and butanol with piperidine. Seems to be something happening in solution.  when TLC is taken both the starting materials merge into one spot on the TLC when in propanol or butanol but when in other solvent together they are still two different spots.  The reaction has been refluxed for 3, 6 12, and 24 hrs.  I always seem to get the di-sub or no reaction any thoughts would be appreciated.
Thanks

[JBL1222]

I was under the impression that a true Knoevenegal condensation had to take place in the presence of an active methylene compound. Your rxn scheme shows a methyl compound. Perhaps this is your problem?