Iodocycloisomerization/Nucleophile Addition Cascade Transformations of 1,2-Alkynediones
Debojyoti Bag1,2, Harpreet Kour1, Nirjhar Saha3
1Natural Products and Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine (CSIR-IIIM), Canal Road, Jammu 180001, Jammu and Kashmir, India.
Abstract:
A general electrophilic iodocyclization/nucleophile addition cascade transformation for 1,2-alkynediones for the synthesis of various oxygen heterocycles and access to regioselective alkyne hydroxylation is reported. Furan-tethered ynediones resulted in the construction of exo-enol ethers via carbonyl-alkyne cyclization-initiated heteroarene dearomatization, whereas other (hetero)arene-, alkenyl-, and alkyl-tethered ynediones resulted in the formation of highly functionalized 3(2H)-furanones. Importantly, the developed domino protocols involve the construction of important heterocyclic scaffolds and installation of two functional groups in a single operation. Moreover, the use of water as a nucleophile resulted in regioselective alkyne hydroxylation via furanone ring opening. The developed protocols are characterized by a wide substrate scope, and their utility has been demonstrated by a number of postsynthetic transformations.
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