The Barton-McCombie Reaction

摘要: Deoxygenations of alcohols, i.e., processes that replace a hydroxyl group with hydrogen at saturated carbon, find applications in both total synthesis and the systematic modifications natural products. They may also be employed to introduce deuterium or tritium site-specific manner. Reductive methods involve ionic highly polarized reagents intermediates can limited their applicability: for example, competing reaction pathways including cationic rearrangements anionic eliminations encountered sterically hindered systems substrates bearing heteroatoms close center undergoing reduction. As evidenced by developments over last few decades, generation direct quenching via atom abstraction derived, carbon-centered radical typically show greatest tolerance presence other functional groups variations steric acid electronic environment vicinity deoxygenation. Derivatization is prerequisite, determinant factors efficient formation deoxygenated product lies ability combination substrate induce homolysis C-O bond coupled induction rapidly reduce free donation, thereby propagating an chain process. A high-yielding way realize this sequence was first described Barton McCombie using free-radical O-thioacyl derivatives secondary alcohols tri-n-butylstannane. This chapter provides detailed description comparison combinations will bring about these summary evaluation alternative deoxygenation methods. Mechanistic stereochemical issues set out scope limitations respect thioacylation reduction steps exemplify some modification products. Keywords: Barton-McCombie reaction; Deoxygenation; Thioacylation; Alcohols; Reduction; Tri-n-butylstannane; O-Thioacyl derivatives; Reagents; Mechanism; Method comparisons; Experimental procedures