Bodipy Derivatives as Organic Triplet Photosensitizers for Aerobic Photoorganocatalytic Oxidative Coupling of Amines and Photooxidation of Dihydroxylnaphthalenes

Abstract

We used iodo-Bodipy derivatives that show strong absorption of visible light and long-lived triplet excited states as organic catalysts for photoredox catalytic organic reactions. Conventionally most of the photocatalysts are based on the off-the-shelf compounds, usually showing weak absorption in the visible region and short triplet excited state lifetimes. Herein, the organic catalysts are used for two photocatalyzed reactions mediated by singlet oxygen ((1)O2), that is, the aerobic oxidative coupling of amines and the photooxidation of dihydroxylnaphthalenes, which is coupled to the subsequent addition of amines to the naphthoquinones, via C-H functionalization of 1,4-naphthoquinone, to produce N-aryl-2-amino-1,4-naphthoquinones (one-pot reaction), which are anticancer and antibiotic reagents. The photoreactions were substantially accelerated with these new iodo-Bodipy organic photocatalysts compared to that catalyzed with the conventional Ru(II)/Ir(III) complexes, which show weak absorption in the visible region and short-lived triplet excited states. Our results will inspire the design and application of new organic triplet photosensitizers that show strong absorption of visible light and long-lived triplet excited state and the application of these catalysts in photoredox catalytic organic reactions.

Picomole‐Scale Real‐Time Photoreaction Screening: Discovery of the Visible‐Light‐Promoted Dehydrogenation of Tetrahydroquinolines under Ambient Conditions

“…[10] The presence of H 2 O 2 in the reaction mixture was detected in a titration reaction with KI (see Figure S34). [11] Tautomerization of the dihydroquinoline intermediate B into C (Scheme 1; these intermediates are almost energetically equal) [12] allows the generation of the final quinoline product through a second dehydrogenation step.…”

Difluoroboranyl derivatives as efficient panchromatic photoinitiators in radical polymerization reactions

“…trans-bis(trialkylphosphine) bisacetylide complex with BODIPY ligand (not styrylBODIPY ligand, s T = 128 ls) [51] or a C 60 -styrylBODIPY dyad (71-123 ls) [52]. However, this lifetime is close to that observed with heavy atom effect (s T = 1.8 ls) [53] or trans-bis-(trialkylphosphine) Pt(II) bisacetylide binuclear complex with BODIPY ligand (s T = 5.8 ls) [54]. It is fair to mention that the spectra are noisy and difficult to more precise interpretation.…”

One‐Pot Enantioselective Synthesis of 1,4‐Naphthoquinone‐Derived Polycycles through Oxidative Dearomatization and Aminocatalysis

“…For the dearomatization step, metal-free iodo-BODIPY 7 was chosen as a photosensitizer due to its ease of synthesis, strong visible light absorption and ability of oxidize phenol derivatives under aerobic conditions. [12] An intensive screening of reaction conditions involving the nature of solvents, photosensitizers, additives, reaction time and oxygen sources has been carried out (see the Supporting Information) and the best results are depicted herein (Scheme 5).…”

“…For the bodipy-photocatalyzed oxidative dearomatization step, the reaction mixture was irradiated with 35-W Xe lamp (0.72 mol L -1 NaNO 2 solution was used as filter so that light with wavelength Ͻ 385 nm was blocked). Dienals 1 [14] and the bodipy photosensitizer 7 [12] were prepared according to literature procedures. Photooxidative Dearomatization/Aminocatalysis.…”