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5-EndoCyclizations of NHC-Boraallyl Radicals Bearing Ester Substituents: Characterization of Derived 1,2-Oxaborole Radicals and Boralactones
- Source :
- Journal of the American Chemical Society; November 2018, Vol. 140 Issue: 46 p15868-15875, 8p
- Publication Year :
- 2018
-
Abstract
- EPR studies of radical hydrogen abstraction reactions of N-heterocyclic carbene (NHC) complexes of alkenylboranes bearing two ester substituents revealed not the expected boraallyl radicals but instead isomeric 1,2-oaxborole radicals. Such radicals are new, and DFT calculations show that they arise from the initially formed boraallyl radicals by a rapid, exothermic 5-endocyclization. These spectroscopic and computational discoveries prompted a series of preparative experiments that provided access to a novel family of robust NHC-boralactones. A one-pot procedure was developed to access the boralactones directly from an NHC-borane (NHC-BH3) and dimethyl acetylenedicarboxylate.
Details
- Language :
- English
- ISSN :
- 00027863 and 15205126
- Volume :
- 140
- Issue :
- 46
- Database :
- Supplemental Index
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Periodical
- Accession number :
- ejs46876493
- Full Text :
- https://doi.org/10.1021/jacs.8b09288