Chemoselective Acylation/Wittig or β‐Acylation Reactions: Diversity‐Oriented Synthesis of Indandione‐Tethered Benzofurans and β‐Acylated Arylidene Indandiones

An efficient, chemoselective, and switchable diversity‐oriented synthesis of β ‐acylated arylidene indandiones and the indanedione‐based formal cross‐coupling benzofuran adducts is reported, which is challenging to realize by conventional strategies. It is achieved via a chemoselective acylation by altering the addition sequence of acylating agents with distinct reactivities, followed by β ‐acylation or chemoselective intramolecular Wittig reactions, with the in situ‐generated bis‐acylated phosphorus ylides as the key intermediates.