A practical and environmentally friendly strategy for generatingalkoxycarbonylradicalsfrom readily available carbazates under metal‐free conditions has been developed. In the presence of tetrabutylammonium iodide and tert‐butyl hydroperoxide, 2‐isocyanobiphenyls smoothly underwent radical alkoxycarbonylation with carbazates to afford phenanthridine‐6‐carboxylates.
A sequential oxidative radical alkoxycarbonylation and aromatization of 2-isocyanobiphenyl with carbazates was developed to furnish phenanthridine-6-carboxylates. Various functional groups such as methoxy, chloro, fluoro, trifluoromethoxy, and trifluoromethyl groups were tolerated well under the reaction conditions. The sequential radical addition-cyclization strategy represents a practical route to access phenanthridine-6-carboxylates.
Metal-free, visible-light-promoted oxidative radical cyclization of <i>N</i>-biarylglycine esters: one-pot construction of phenanthridine-6-carboxylates in water
作者:Palani Natarajan、Deachen Chuskit、Priya Priya
DOI:10.1039/c9gc01557d
日期:——
A metal-free, visible-light (blue LED: hν = 425 ± 15 nm) photoredox-catalyzed intramolecular cyclization reaction of N-biarylglycine esters to phenanthridine-6-carboxylates in water under an open air atmosphere at ambient conditions has been developed. A plausible mechanism is proposed for the reaction. Using a catalytic amount (5 mol%) of rose bengal and a blue LED, the N-biarylglycine esters were