Visible Light-Induced Carbonylation Reactions with Organic Dyes as the Photosensitizers

Synthesis of Bis(3-indolyl)methanes Mediated by Potassium tert-Butoxide

The indole moiety is an important N-heterocycle found in natural products, and a key structural component of many value-added chemicals including pharmaceuticals. In particular, bis(3-indolyl)methanes (BIMs) are an important subgroup of indoles, composed of two indole units. Herein, we report the development of a simple method to access BIMs derivatives in yields of up to 77 % by exploiting a tBuOK-mediated coupling reaction of indoles and benzyl alcohols.

Oxidative C-H/N-H Carbonylation of Benzamide by Nickel Catalysis with CO as the Carbonyl Source

An efficient and direct carbonylation of aminoquinoline benzamides has been developed using abundant and inexpensive Ni(OAc)₂·4H₂O as the catalyst and carbon monoxide as a cost-efficient C1 building block. This process features good functional-group tolerance and can be conducted on gram scale. The directing group can be easily removed under mild conditions.

Catalytic Oxidative Cleavage of C(OH)-C Bonds in Lignin Model Compounds to Carboxylic Acids by Fe(NO3)3.9H2O/NaI/DMSO

The secondary C(OH)-C bonds are abundant in biomass such as lignin and cellulose. Thus, selective cleavage of the C(OH)-C bonds into value chemicals attracted much attention. Molecular iodine has received considerable attention as an inexpensive and readily available catalyst to yield the corresponding products in excellent yields with high selectivity, but it is highly corrosive and toxic, making its use somewhat unattractive. In this study, I₂ was generated in situ from Fe(NO₃)₃.9H₂O/NaI, which was further combined with Fe(NO₃)₃.9H₂O to catalyze the oxidation process. In the reaction, the H₂O molecule from the reaction and Fe(NO₃)₃.9H₂O attacked the phenylglyoxal to form benzaldehyde, which was further oxidized to benzoic acid. Aryl primary and secondary benzylic alcohols from lignin were successfully transformed into aryl carboxylic acids by Fe(NO₃)₃.9H₂O/NaI/DMSO. The catalytic system was green and efficient, avoiding the usage of toxic and corrosive molecular I₂. From the experiments, it was clear that the yield of the product from the substrates with an electron-donating group was higher than that of electron-withdrawing substituted substrates, which was similar to the aryl secondary alcohols. Aryl alkyl ketones were also successfully conducted by the Fe(NO₃)₃.9H₂O/NaI/DMSO catalytic system.

Advances in Visible-Light-Mediated Carbonylative Reactions via Carbon Monoxide (CO) Incorporation

The abundant and inexpensive carbon monoxide (CO) is widely exploited as a C1 source for the synthesis of both fine and bulk chemicals. In this context, photochemical carbonylation reactions have emerged as a powerful tool for the sustainable synthesis of carbonyl-containing compounds (esters, amides, ketones, etc.). This review aims at giving a general overview on visible light-promoted carbonylation reactions in the presence of metal (Palladium, Iridium, Cobalt, Ruthenium, Copper) and organocatalysts as well, highlighting the main features of the presented protocols and providing useful insights on the reaction mechanisms.

Visible-Light-Induced Carbonylation of Indoles with Phenols under Metal-Free Conditions: Synthesis of Indole-3-carboxylates

A visible-light-induced carbonylation of indoles with phenols for the synthesis of indole-3-carboxylates has been developed. The reaction proceeded via a radical carbonylation process in which elementary I₂ was used as an effective photosensitive initiator and, thus, avoided the use of transition metal catalysts. A series of different aryl indole-3-carboxylates were prepared in moderate to good yields. The broad applicability of this methodology was further highlighted by the late-stage functionalization of several phenol-containing natural products and pharmaceuticals.

Visible-Light-Induced Palladium-Catalyzed Dehydrogenative Carbonylation of Amines to Oxalamides

The palladium-catalyzed oxidative carbonylation of amines toward the synthesis of oxalamides has been established around 30 years ago and it usually needs the presence of (over)stoichiometric amounts of oxidant. In this work, the first transformation of this type in which the oxidant was replaced by visible light is described. The new approach uses a simple robust Pd complex, which can even be partially recycled. A mechanistic reason is provided and supported by control experiments and EPR studies, showing that Pd^I was formed and Pd⁰ was the active species. Both nitrogen- and the intermediate acyl radical can be detected. Moreover, the formation of hydrogen was confirmed by gas GC.

Tandem Photoredox Catalysis: Enabling Carbonylative Amidation of Aryl and Alkylhalides

We report a new visible-light-mediated carbonylative amidation of aryl, heteroaryl, and alkyl halides. A tandem catalytic cycle of [Ir(ppy)₂ (dtb-bpy)]⁺ generates a potent iridium photoreductant through a second catalytic cycle in the presence of DIPEA, which productively engages aryl bromides, iodides, and even chlorides as well as primary, secondary, and tertiary alkyl iodides. The versatile in situ generated catalyst is compatible with aliphatic and aromatic amines, shows high functional-group tolerance, and enables the late-stage amidation of complex natural products.

Synthesis and characterization of a triphenylamine-dibenzosuberenone-based conjugated organic material and an investigation of its photovoltaic properties

3,7-Bis[4-(diphenylamino)phenyl]-5 H-dibenzo[ a,d][7]annulen-5-one, containing triphenylamine- and dibenzosuberenone-based donor-acceptor-donor (D-A-D) conjugated moieties, is synthesized in high yield by Suzuki coupling of 5 H-dibenzo[ a,d][7]annulen-5-one with [4-(diphenylamino)phenyl]boronic acid. The most important part of the present study is the creation of a dye-sensitized solar cell structure using the synthesized organic molecule for the first time and the power conversion efficiency of this structure. Three solar cell devices are prepared and are named as first device, second device, and third device. The power conversion efficiency (%) value for first device, second device, and third device is calculated as 2.54, 2.38, and 2.54, respectively. Moreover, the chemical structure of the synthesized compound is determined by nuclear magnetic resonance, infrared, ultraviolet visible, fluorescence spectroscopy, and high-resolution mass spectrometry.

Palladium-catalyzed carbonylative synthesis of arylacetamides from benzyl formates and tertiary amines

A palladium-catalyzed carbonylative synthesis of arylacetamides via a C–N bond cleavage of tertiary amines with benzyl formates as the CO source has been disclosed. A variety of arylacetamides were obtained in very good yields under oxidant-free conditions.

Deaminative carbonylative coupling of alkylamines with styrenes under transition-metal-free conditions

Transition-metal-free deaminative carbonylation through C–N bonds activation via Katritzky salts has been successful developed. Various α,β-unsaturated ketones were obtained in moderate to good yields with alkylamines and styrenes as the substrates.

Singlet oxygen mediated dual C–C and C–N bond cleavage in visible light

A tandem cleavage of carbon–carbon and carbon–nitrogen bonds in imidazo[1,2-a]pyridines and imidazo[1,2-a]quinolines is reported in the presence of eosin Y and visible light.

Palladium-catalyzed C3-selective C–H oxidative carbonylation of imidazo[1,2-a]pyridines with CO and alcohols: a way to access esters

A palladium-catalyzed C3-selective C–H oxidative carbonylation for the synthesis of various esters from imidazo[1,2-a]pyridines and CO with high efficiency and high atom economy has been developed.

Selenium-Catalyzed Carbonylative Synthesis of 3,4-Dihydroquinazolin-2(1H)-one Derivatives with TFBen as the CO Source

An efficient and general carbonylative procedure for the synthesis of 3,4-dihydroquinazolin-2(1H)-one from 1-(halomethyl)-2-nitrobenzenes and aryl/alkyl amines have been explored. In this approach, to avoid of using toxic CO gas, a solid and stable CO precursor, TFBen (benzene-1,3,5-triyl triformate), was utilized. With elemental selenium as the catalyst, a variety of aryl/alkyl amines has been tolerated well to afford the corresponding 3,4-dihydroquinazolin-2(1H)-one products in moderate to excellent yields under mild reaction condition.

Carbonylative transformation of benzyl formates into alkyl 2-arylacetates in organic carbonates

A carbonylation procedure for the transformation of benzyl formates in organic carbonates has been developed.

Recent advances of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) in photocatalytic transformations

In this review, the recent advances of the application of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) as a photoredox catalyst in the past three years (2016–2018) for various organic reactions are summarized.

Phosphite-catalyzed alkoxycarbonylation of aryl diazonium salts

In this communication, an interesting phosphite-catalyzed alkoxycarbonylation of aryl diazonium salts has been reported. At room temperature and under CO pressure, moderate to good yields of the desired esters can be produced in the absence of bases or any other additives.

Non-noble metal-catalysed carbonylative transformations

The main achievements on non-noble metal (Mn, Fe, Cu, Co, Ni) catalysed carbonylative transformations have been summarized and discussed.

DBU-promoted carbonylative synthesis of 1,3-oxathiolan-2-ones from propargylic alcohols with TFBen as the CO source

A DBU-promoted carbonylative cyclization of propargylic alcohols with sulfur was developed.

Palladium-catalyzed synthesis of quinolin-2(1H)-ones: the unexpected reactivity of azodicarboxylate

A Pd(ii)-catalyzed synthesis of quinolin-2(1H)-ones from quinoline N-oxides with azodicarboxylates as the activating agent has been developed.