Synthesis Of Dihydrochalon From Acryloyl Chlorides And Benzene Via The Tandem Fridel-Crafts Acylation-alkylation

Dihydrochalcone, the structure of which can be described as1,3-diphenylphenylpropan-1-one, is an important synthon in organicchemistry. There are a couple of ways to synthesis of dihydrochalcones,essentially by the catalytic hydrogenation of chalcones or constructingC-C single bond, herein, we report a concise method using acryloylchloride and benzene as reactants via a tandem Fridel-Craftsacylation/alkylation reaction to synthesize dihydrochalcones in moderateto good yields (up to81%). We also investigated the reaction mechanismthoroughly with the DFT calculation.In our research, the reaction of benzene and acryloyl chloride wasselected as a model reaction to optimize the reaction temperature,adding time of acrloyl chloride, catalyst and the amount of catalystloaded. In the experiments, it was observed that yields ofdihydrochalcones and the byproduct1-indanones varied greatlydepending on the substituent(s) of acryloyl chlorides and reactiontemperature. To explain this phenomenon, we investigated the reactionmechanism with the density functional theory calculation, and proposed that there is a six-membered ring H-transfer transition state in theformation of dihydrochalcones, the computed results are in goodagreement with the experimental results.This approach to synthesis of dihydrochalcone is free of expensivetransition metal catalyst and complex high pressure conditions. Thus, itprovides a convenient method to synthesize this kind of compounds, thebyproduct1-indanones are another important organic intermediates aswell.