Metal‐Free Synthesis of Oxa Spiro‐indene‐1,3‐dione Tetrahydrofurans and Pyrans via [3+2]/[4+2] Spirocyclization of 2‐Arylidene‐1,3‐indanedione With Haloalcohols

Abstract

A concise and efficient method has been developed for the synthesis of pharmacologically important spiro‐indene‐1,3‐dione‐ fused tetrahydrofurans and pyrans via a base‐mediated cascade [3+2]/[4+2] spirocyclization of 2‐arylidene‐1,3‐indandiones and 2‐(3‐phenylallylidene)‐indandione with haloalcohols. This protocol offers several advantages, including a straightforward reaction process, short reaction times, broad substrate scope, high product yields, and mild, transition‐metal‐free reaction conditions. The practicality of this approach has been validated through gram‐scale synthesis, which furnished the desired products in good yields.