Continuous Flow β‐Zeolite Catalysed Regioselective Alkylation of Naphthols Using Alcohols for Synthesis of Peroxynaphthalen‐2(1H)‐one, Azidonaphthalen‐2(1H)‐one and Fluoronaphthalen‐2(1H)‐one Derivatives

Functionalized naphthols are recognized as prominent scaffolds in organic synthesis and materials chemistry. Continuous flow alkylation of α- and β-naphthols was demonstrated using various primary and secondary benzylic alcohols in the presence of environmentally benign granular β-zeolite as a reusable catalyst. For a variety of β-naphthols, the respective alkylated products were obtained with good regioselectivity and high yields under mild reaction conditions. The protocol was carried out via the classical Friedel-Crafts type alkylation process, with stable carbocations generated as intermediates. Using this protocol, versatile naphthol derivatives were synthesized from primary and secondary benzylic alcohols (50 and 44 examples in batch and continuous flow processes, respectively), achieving good yields. Key advantages of the process include rapid and efficient transformation, facilitation of gram-scale synthesis, and generation of water as the sole by-product. The continuous reusability of granular β-zeolite was demonstrated, further emphasizing the sustainability of the method. The application of alkylated naphthols for quaternary functionalization was shown through peroxidation, azidation, and halogenation reactions conducted under a continuous flow module, resulting in the respective peroxynaphthalen-2(1H)-one, azidonaphthalen-2(1H)-one, and fluoronaphthalen-2(1H)-one derivatives.

• Londhe, G
• Bokade, V
• Gnanaprakasam, B

• Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune, 411008 India

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