Efficient Synthesis of the Cyclization Intermediate of Iso E Super

The Diels–Alder (DA) reaction between 3-methyl-3-penten-2-one (MP) and myrcene is experimentally examined and theoretically modeled as part of the Iso E Super synthesis process. The results reveal that the DA reaction between MP and myrcene follows a typical electron-demand mechanism, and the para-product (2) is the most stable structure. With the addition of the AlCl3 catalyst, the reaction energy barrier drops significantly from 132.85 to 61.38 kJ/mol, easing the reaction conditions. The AlCl3 catalyst exhibits the highest catalytic activity among the catalysts tested, especially in isooctane solvent, of which the conversion of myrcene reaches 88.51% and the total selectivity for the cyclization intermediate of Iso E Super is 92.86%. Additionally, it was observed that increasing the Lewis acidity strength leads to higher conversion and selectivity for the para-product of myrcene. This can be attributed to the enhanced electrophilicity of the second carbon atom in MP upon interaction with the catalyst, which makes it more reactive towards the electron-rich carbon atoms of myrcene.