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Keywords: phosphine; cyclization; coumarin; furanone EN phosphine cyclization coumarin furanone 1587 1592 6 07/31/23 20230815 NES 230815 Graph Furan and tetrahydrofuran heterocycles are distributed widely in nature, and they are also prevalent building blocks in a vast array of pharmaceutically active molecules (Figure 1). [116] Otherwise, coumarin-fused bicyclo[3.2.0]heptenones will be produced via a phosphine-promoted tandem [3+2] cyclization/intramolecular Wittig cyclization performing the reaction in toluene or THF, which has been disclosed in our previous study. [96] Very recently, coumarin-fused cyclopentanones were selectively afforded in moderate to good yields with excellent diastereoselectivities under phosphine catalysis of 3-benzoyl coumarin with alkynone (Scheme 1c). [95] Followed by that, we then discovered an efficient method for the synthesis of coumarin-fused bicyclo[3.2.0]heptenones via phosphine-promoted tandem [3+2] cyclization/intramolecular Wittig cyclization from 3-aroylcoumarin and alkynone (Scheme 1b). [Extracted from the article]