10.1039/c4ra04689g
The research explores a novel method for synthesizing dihydrobenzofurans, which are key structural components in many biologically active compounds. The study investigates the tandem Claisen rearrangement and intramolecular hydroaryloxylation of allyl phenyl ethers in subcritical water (SBW) using various zeolite catalysts (SBA-15, TS-1, and HZSM-5). The experiments were conducted at temperatures ranging from 200 to 320 °C, with HZSM-5 demonstrating the highest catalytic activity. The study found that temperature and catalyst type significantly influenced product yields, with 2-methyl-2,3-dihydrobenzofuran being the primary product. The optimal reaction conditions were identified as 260 °C with an APE–water molar ratio of 1:40, yielding 65% of the desired product. The HZSM-5 catalyst showed high selectivity and recyclability, maintaining its activity over multiple uses. The study also tested various allyl phenyl ether derivatives, achieving high yields (83–95%) of corresponding dihydrobenzofurans.