Calixarenes with a conjugated substituent at a methylene bridge position are of interest for the effect the substituent has on macrocycle conformation and electronic structure. The Heck reaction appears to be a route to a variety of substituted 2-benzylidene calixarenes, including those with electron-donating or electron-withdrawing groups at the para position on the benzylidene ring. In a typical synthesis, the 2-methylene-p-tert-butyltetramethoxycalixarene 1 was demethylated by treatment with iodocyclohexane in DMF at 140 °C. The resulting product, a 2-methylene-p-tert-butyltetrahydroxycalixarene (2), was the substrate for subsequent Heck reactions. In a successful reaction, compound 2 reacted with 4-iodoanisole in a palladium-catalyzed reaction, yielding the p-methoxy-benzylidene calixarene 3. The synthesis of other substituted benzylidenes by similar methods is underway.

Synthesis of substituted 2-benzylidenecalixarenes via Heck reaction of 2-methylene-p-tert-butyltetrahydroxycalix[4]arene

2019 Spring National Meeting

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