An acid-mediated synthesis of substituted naphthalenes from ortho-alkynyl tertiary benzylic alcohols

Abstract

We present an efficient, acid-mediated cascade strategy for the construction of 1,3- and 1,2,3-substituted naphthalenes from readily accessible starting materials. This method employs ortho-alkynyl or arynyl tertiary benzylic alcohols as the substrates, which undergo a Lewis acid-triggered dehydration to form ortho-(alkynyl)-styrene intermediates. These intermediates subsequently undergo intramolecular cycloaromatization, resulting in the formation of substituted naphthalenes in a one-pot reaction. A significant advantage of this approach is its ability to proceed under sustainable and neat reaction conditions using ZnCl₂ as the sole Lewis acid, highlighting the simplicity and practicality of the process. Additionally, the strategy exhibits a broad substrate scope, efficiently yielding the desired naphthalene derivatives with practical and consistent yields. This method not only simplifies the synthetic pathway but also aligns with green chemistry principles by minimizing the use of solvents and reagents.