An enantio‐ and diastereoselective sp3‐sp3 coupling of acyclic/cyclic ketones with dihydrodibenzo‐oxazepines has been developed by merging visible light photo‐redox‐ or electro‐catalysis with organocatalysis. This approach parallelly utilizes Eosin Y or graphite electrodes for the co‐catalyst‐free oxidative conversion of dihydrodibenzo‐oxazepines to oxazepines, followed by L‐Proline catalyzed direct Mannich‐type reaction with ketones. A series of enantioenriched dihydrodibenzo‐oxazepines have been prepared in high yields and enantioselectivity. This method shows substantial advantages over the existing protocols by using potentially safer starting materials and cheap commercially available catalysts.

Despite the persistent presence of medium-sized (seven- to nine-membered) scaffolds in natural products and biologically active molecules, their asymmetric syntheses have always been considered a formidable task; therefore remained underdeveloped...

We disclose herein electro-oxidative synthesis as the general protocol for procuring phenazines under mild reaction conditions. Using aerial oxygen as an oxidant, inexpensive electrolyte, and electrodes, a diverse range of phenazines have been accessed in good yields via the ring contraction of 10,11-dihydro-5H-dibenzo­[b,e]­[1,4]­diazepines. In addition, the syntheses of phenazines and diamino phenazines via direct electro-oxidation of dihydrophenazines and electro-dimerization of o-phenylenediamines, respectively, have also been accomplished.

No abstract

No abstract