Cobalt-Catalyzed Asymmetric Hydroboration/Cyclization of 1,6-Enynes with Pinacolborane
Songjie YuDepartment of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, SingaporeCaizhi WuDepartment of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, SingaporeShaozhong GeDepartment of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
2017en
ABI
Abstract
We report a cobalt-catalyzed asymmetric hydroboration/cyclization of 1,6-enynes with catalysts generated from Co(acac)2 and chiral bisphosphine ligands and activated in situ by reaction with pinacolborane (HBpin). A variety of oxygen-, nitrogen-, and carbon-tethered 1,6-enynes underwent this asymmetric transformation, yielding both alkyl- and vinyl-substituted boronate esters containing chiral tetrahydrofuran, cyclopentane, and pyrrolidine moieties with high to excellent enantioselectivities (86%–99% ee).
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