New synthetic methodologies to functionalize 3,4-Dihydroquinoxalin-2-Ones and 3,4-Dihydro-1,4- Benzoxazin-2-Ones using visible-light photocatalysis

Resumen

In this thesis, several synthetic approaches for the C-3 functionalization of 3,4-dihydroquinoxalin-2-ones and 3,4 dihydro-1,4-benzoxazin-2- ones using visible-light photoredox catalysis are presented. The thesis is divided into three different parts, being the first one a general introduction and the main objectives. Then, in the second part, the efforts on the nucleophilic functionalization of 3,4-dihydroquinoxalin-2-ones and 3,4-dihydro-1,4-benzoxazin-2-ones with are presented. Specifically, we developed synthetic protocols for the Friedel-Crafts reaction between 3,4-dihydroquinoxalin-2-ones and 3,4-dihydro-1,4-benzoxazin-2-ones with indoles and other electron-rich arenes (chapter 1). Besides, we identified reaction conditions for the asymmetric oxidative Mannich reaction using a combination of photoredox catalysis and organocatalysis (chapter 2). Additionally, we could develop a strategy to react 3,4-dihydroquinoxalin-2-ones with pyrazol-3-ones (chapter 3). The last contribution in the nucleophilic functionalization part was the copper-catalyzed alkynylation of 3,4-dihydroquinoxalin-2-ones with terminal alkynes (chapter 4)The third part of this thesis encompasses the electrophilic functionalization of 3,4-dihydroquinoxalin-2-ones and 3,4-dihydro-1,4-benzoxazin-2-ones. Initially, we developed a dual catalytic system based on photoredox catalysis for the Giese reaction between 3,4-dihydroquinoxalin-2-ones and electron-poor alkenes (chapter 5). Thereafter, we presented our approach on the amination of 3,4-dihydroquinoxalin-2-ones and 3,4-dihydro-1,4-benzoxazin-2-ones with dialkyl azodicarboxylates (chapter 6). Then, we developed a 1,2-addition reaction of 3,4-dihydroquinoxalin-2-ones to trifluoromethyl ketones through visible-light photoredox catalysis (chapter 7). Lastly, an organophotoredox-catalyzed 1,6-addition reaction of 3,4-dihydroquinoxalin-2-ones to p-quinone methides is presented (chapter 8).