title: Catalyst-Free Synthesis of Borylated Lactones from Esters via Electrophilic Oxyboration.
abstract: A catalyst-free oxyboration reaction of alkynes is developed. The resulting borylated isocoumarins and 2-pyrones are isolated as boronic acids, pinacolboronate esters, or potassium organotrifluoroborate salts, providing a variety of bench-stable organoboron building blocks for downstream functionalization. This method has functional group compatibility, is scalable, and proceeds with readily available materials: B-chlorocatecholborane and methyl esters. Mechanistic studies indicate that the B-chlorocatecholborane acts as a carbophilic Lewis acid toward the alkyne, providing a mechanistically distinct pathway for oxyboration that avoids B-O σ bond formation and enables this catalyst-free route.
authors: Department of Chemistry, University of California , Irvine, California 92617-2025, United States.
authors: Darius J
authors: DJ
authors: Faizi
authors: Department of Chemistry, University of California , Irvine, California 92617-2025, United States.
authors: Adena
authors: A
authors: Issaian
authors: Department of Chemistry, University of California , Irvine, California 92617-2025, United States.
authors: Ashlee J
authors: AJ
authors: Davis
authors: Department of Chemistry, University of California , Irvine, California 92617-2025, United States.
authors: Suzanne A
authors: SA
authors: Blum
mesh_terms: D001881:Borates / Q000737:chemistry*; D004952:Esters / Q000737:chemistry*; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure
chemical_list: D001881:Borates; D004952:Esters; D007783:Lactones