Visible‐Light‐Induced Photocatalyst‐Free Oxidative Cyclization of Primary Alcohols by Selectfluor via HAT Process: Synthesis of Quinazolinones and Benzothiadiazines

Abstract

A mild and convenient method for oxidative cyclization of primary alcohols with o-aminobenzamides and o-aminobenzenesulfonamides to achieve quinazolinones and benzothiadiazines by selectfluor under visiblelight irradiation was reported. Selectfluor is used as hydrogen atom transfer reagent for oxidative cyclization under visible light irradiation. This photochemical approach offers broad substrate scope of quinazolinones and benzothiadiazines under mild reaction conditions.

Dithionite-Mediated Tandem Nitro Reduction/Imine Formation/Intramolecular Cyclization for the Synthesis of Dihydro-benzothiadiazine-1,1-dioxides

“…1 H NMR (600 MHz, DMSO-d 6 ) δ 8.12 (s, 1H), 8.00− 7.95 (m, 2H), 7.89 (d, J = 7.8 Hz, 1H), 7.66 (t, J = 7.8 Hz, 1H), 7.51 (dd, J = 8.0, 1.2 Hz, 1H), 7.42 (s, 1H), 7.31 (t, J = 7.0 Hz, 1H), 6.87 (d, J = 8.2 Hz, 1H), 6.77 (t, J = 7.1 Hz, 1H), 5.87 (d, J = 12.0 Hz, 1H). 13…”

“…21 1 H NMR (600 MHz, DMSO-d 6 ) δ 7.94 (d, J = 12.0 Hz, 1H), 7.86 (dd, J = 7.8, 1.7 Hz, 1H), 7.70 (dd, J = 8.1, 1.1 Hz, 1H), 7.54−7.49 (m, 2H), 7.42 (s, 1H), 7.37 (td, J = 7.7, 1.7 Hz, 1H), 7.31 (ddd, J = 8.6, 7.2, 1.5 Hz, 1H), 6.88 (d, J = 8.0 Hz, 1H), 6.77 (t, J = 7.1 Hz, 1H), 6.12 (d, J = 12.0 Hz, 1H). 13…”

“…Based on the control experiment and literature reports, 19,20 doublet; dt, triplet of doublet; t, triplet; m, multiplet. 13 C NMR spectra were recorded with complete proton decoupling. Column chromatography was performed using silica gel (60−120 mesh).…”

Metal-free photoredox-catalyzed direct α-oxygenation of N,N-dibenzylanilines to imides under visible light

“… 25 Recently, our group established visible-light-induced metal-involved and metal-free photocatalyzed organic transformations deploying molecular oxygen as a green oxidant. 26 Also, our group has published work on the α-oxidation of N , N -dibenzylanilines to amides via oxidative C–N cleavage as a prominent product in the presence of rose bengal as a photocatalyst and O 2 . 26 d However, to the best of our knowledge, direct α-oxygenation of amines to imides has not yet been reported.…”

Quinazolinones/Benzothiadiazines as Amidyl/Aminyl Radical Precursors for Controlled Cascade Cyclization via Photocatalyzed PCET

“…Our group has reported photoredox-catalyzed organic transformations − and more recently amidyl radical addition to C–C triple bonds via a PCET process for the controlled synthesis of isoquinoline-1,3,4­(2 H )-triones, 3-hydroxyisoindolin-1-ones, and phthalimides . To the best of our knowledge, the direct formation of cyclic NCRs from N–H bonds without prefunctionalization of quinazolinone amidyl/dihydrobenzothiadiazine aminyl radicals followed by radical cascade cyclizations has not been reported to date.…”