Solid-supported acid-catalyzed C3-alkylation of 4-hydroxycoumarins with secondary benzyl alcohols: access to 3,4-disubstituted coumarins via Pd-coupling

An efficient and operationally simple method for C3-alkylation of 4-hydroxycoumarins has been developed under acidic medium giving good yields of the products. In the present method, a reusable Amberlite (R) IR-120 (H(-) form) was used as an acid catalyst and secondary benzyl alcohols were used as alkylating agents. The obtained 3-alkylated-4-hydroxycoumarins offered an easy access for the synthesis of 3,4-dissubstituted coumarins by way of Pd-catalyzed coupling reactions. (C) 2008 Elsevier Ltd. All rights reserved.