The Redox-Neutral Approach to CH Functionalization

• Published in: Chemistry : a European journal Vol. 19; no. 40; pp. 13274 - 13287
• Main Authors: Peng, Bo, Maulide, Nuno
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 27.09.2013; WILEY‐VCH Verlag
• Subjects: Activation; Asymmetry; atom economy; Classification; CH activation; CH functionalization; hydride transfer; Hydrides; Inert; Nucleophiles; redox chemistry; State of the art; Strategy; CH activation; atom economy; CH functionalization; hydride transfer; redox chemistry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201301522

The direct functionalization of CH bonds is an attractive strategy in organic synthesis. Although several advances have been made in this area, the selective activation of inert sp3 CH bonds remains a daunting challenge. Recently, a new type of sp3 CH activation mode through internal hydride transfer has demonstrated the potential to activate remote sp3 CH linkages in an atom‐economic manner. This Minireview attempts to classify recent advances in this area including the transition to non‐activated sp3 CH bonds and asymmetric hydride transfers. Do it the redox‐neutral way: A hydride transfer process can occur between an sp3 CH bond and a suitably located internal oxidative functional group, leading to a putative zwitterionic intermediate. This intermediate may then undergo cyclization or suffer capture by an external nucleophile, providing CH functionalization products (see scheme). The synthetic value and state‐of‐the‐art of these recently rediscovered strategies is exposed and discussed in this Minireview.