Recent Advances in Synthetic Strategies to 2,3-Dihydrobenzofurans

This review gives an overview on recent developments in methods for the construction of compounds with the 2,3-dihydrobenzo­furan core in the period 2012 to 2019. Interest in 2,3-dihydrobenzofurans is constantly increasing. The methods are divided into intermolecular and intramolecular approaches. Intermolecular approaches are subdivided according to the parent intermediate for the key reaction, while intermolecular approaches are subdivided according by which bond is formed in the key reaction. The transformation of benzofurans to dihydrobenzofurans and other miscellaneous methods are also discussed. Approaches useful for the synthesis of natural products are emphasized. 1 Introduction 2 Intermolecular Approaches 2.1 o-Quinone Methides and o-Quinones 2.2 p-Quinone Methides and p-Quinones 2.3 Nitrogen-Containing Phenols and Quinones 2.4 o-Hydroxyphenylcarbonyl Derivatives and Phenols 2.5 Miscellaneous 3 Intramolecular Approaches 3.1 O–C2 Bond Forming 3.2 C2–C3 Bond Forming 3.3 C3–Aryl Bond Forming 3.4 O–Aryl Bond Forming 4 From BF to DHB 5 Rearrangements and Aromatizations