Progress Toward the Synthesis of Novel Heterocyclic Compounds: Via Diels-Alder Reactions, Including Microwave Promotion

Benzofurazan 1 was reacted with 4,5-diphenyl-1,3-dioxol-2-one 2 in refluxing toluene. No reaction (NR) was detected by TLC analysis, as indicated below. It was decided that a higher-boiling solvent should be used. Accordingly, in the next trial, the same two reactants were used but this time with refluxing mesitylene as the solvent. A TLC analysis indicated a product was formed, but both reactants were still present in the reaction mixture. Another experiment with these conditions was run with a 30% excess of benzofurazan, to try to get all of the 4,5-diphenyl-1,3-dioxol-2-onetoreact. However, a TLC analysis of this reaction mixture showed the same results. A longer reflux of this run resulted in multiple products showing upon the TLC. In a final endeavor to push this reaction to completion (with reactants hopefully absent) but with a single product, refluxing 5-tert-butyl-m-xylene was used as the solvent, to see if the higher boiling point would make a difference. But, the TLC revealed two products in the reaction mixture along with some of the two reactants (still present). It was unclear as to if the expected product (3) was formed