Combining the catalytic enantioselective reaction of visible-light-generated radicals with a by-product utilization system

• Main Authors: Huang, Xiaoqiang, Luo, Shipeng, Burghaus, Olaf, Webster, Richard David, Harms, Klaus, Meggers, Eric
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2017
• Subjects: By-product Utilization; Enantioselective Radicals
• Online Access: https://hdl.handle.net/10356/86888; http://hdl.handle.net/10220/44207
• Institution: Nanyang Technological University

We report an unusual reaction design in which a chiral bis-cyclometalated rhodium(III) complex enables the stereocontrolled chemistry of photo-generated carbon-centered radicals and at the same time catalyzes an enantioselective sulfonyl radical addition to an alkene. Specifically, employing inexpensive and readily available Hantzsch esters as the photoredox mediator, Rh-coordinated prochiral radicals generated by a selective photoinduced single electron reduction are trapped by allyl sulfones in a highly stereocontrolled fashion, providing radical allylation products with up to 97% ee. The hereby formed fragmented sulfonyl radicals are utilized via an enantioselective radical addition to form chiral sulfones, which minimizes waste generation.