Aminopyridine‐Borane Complexes as Hydrogen Atom Donor Reagents: Reaction Mechanism and Substrate Selectivity. Issue 54 (24th August 2017)

• Record Type: Journal Article
• Authors: Barth, Florian; Achrainer, Florian; Pütz, Alexander M.; Zipse, Hendrik
• Is Part Of: Chemistry. Volume 23:Issue 54(2017)
• Page Start: 13455
• Page End: 13464
• Publication Date: 2017-08-24
• Subjects: borane complexes -- hydrogen-atom transfer -- Lewis base -- NMR spectroscopy -- radical reactions; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201702469
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Lewis base‐borane complexes are shown to be potent hydrogen atom donors in radical chain reduction reactions. Results obtained in 1 H, 11 B, and 13 C NMR measurements and kinetic experiments support a complex reaction mechanism involving the parent borane as well as its initial reaction products as active hydrogen atom donors. Efficient reduction reactions of iodides, bromides, and xanthates in apolar solvents rely on initiator systems generating oxygen‐centered radicals under thermal conditions and pyridine‐borane complexes carrying solubilizing substituents. In contrast to tin hydride reagents, the pyridine‐boranes reduce xanthates faster than the corresponding iodides. Abstract : Alternative for tin hydrides : The crucial choice of initiators and reaction conditions for Lewis base borane mediated radical chain reduction reactions has been investigated in detail. An inverted selectivity was found for the reduction of iodides versus xanthates as compared to tin hydride reagents.