Phosphine-Catalyzed Chemoselective Reduction/Elimination/Wittig Sequence for Synthesis of Functionalized 3-Alkenyl Benzofurans

A Comprehensive Review on Benzofuran Synthesis Featuring Innovative and Catalytic Strategies

Benzofurans have intrigued both pharmaceutical researchers and chemists owing to the medicinal usage of their derivatives against copious disease-causing agents (i.e., bacteria, viruses, and tumors). These heterocyclic scaffolds are pervasively encountered in a number of natural products and drugs. The ever-increasing utilization of benzofuran derivatives as pharmaceutical agents persuaded the chemists to devise novel and facile methodological approaches to assemble the biologically potent benzofuran nucleus. This review summarizes the current developments regarding the innovative synthetic routes and catalytic strategies to procure the synthesis of benzofuran heterocycles with their corresponding mechanistic details, reported by several research groups during 2021-2023.

PPh3-Triggered Tandem Synthesis of 2,3-Disubstituted Benzofuran Derivatives from o-Quinone Methides with Acyl Chlorides

A PPh₃-triggered tandem strategy for the efficient synthesis of valuable 2,3-disubstituted benzofuran derivatives in generally good to high yields from aryl or alkyl acyl chlorides and o-quinone methides has been developed. This method features mild reaction conditions, simple operation, and a broad substrate scope.

Phosphine-Mediated [4 + 3] Annulation of Diynoates and 2-Arylidene Indane-1,3-diones: Access of Indeno[1,2-b]oxepin-4-ylidenes and Beyond

A novel unprecedented triphenylphosphine-mediated [4 + 3] annulation reaction of 2-benzylidene indane-1,3-diones and -diynoates through initial phosphine α-addition was discovered and found to result in biologically interesting indeno[1,2-b]oxepin-4-ylidenes in up to 75% yield. The seven-membered separable Z and E isomeric oxepins were confirmed using single-crystal X-ray diffraction.