Direct 3-Acylation of Indolizines by Carboxylic Acids for the Practical Synthesis of Red Light-Releasable Caged Carboxylic Acids

Advances in organocatalyzed synthesis of organic compounds

The recent advancements in utilizing organocatalysts for the synthesis of organic compounds have been described in this review by focusing on their simplicity, effectiveness, reproducibility, and high selectivity which lead to excellent product yields. The organocatalytic methods for various derivatives, such as indoles, pyrazolones, anthrone-functionalized benzylic amines, maleimide, polyester, phthalimides, dihydropyrimidin, heteroaryls, N-aryl benzimidazoles, stilbenoids, quinazolines, quinolines, and oxazolidinones have been specifically focused. The review provides more understanding by delving into potential reaction mechanisms. We anticipate that this collection of data and findings on successful synthesis of diverse compound derivatives will serve as valuable resources and stimulating current and future research efforts in organocatalysis and industrial chemistry.

Clickable bisreactive small gold nanoclusters for preparing multifunctionalized nanomaterials: application to photouncaging of an anticancer molecule

In this study, we successfully synthesized a small-sized gold nanocluster (2 nm) coated with homogeneous tripeptides bearing azido and amino groups that enable facile multifunctionalizations. Using sodium phenoxide to reduce tetrachloroauric(iii) acid in the presence of the cysteine-containing tripeptide, we efficiently prepared the gold nanoclusters without damaging the azido group. We then utilized this clickable bisreactive nanocluster as a versatile platform for synthesizing multifunctionalized gold nanomaterials. The resulting nanoclusters were conjugated with an anticancer compound connected to an indolizine moiety for photoinduced uncaging, a photodynamic therapy agent acting as a photosensitizer for uncaging, and a cyclic RGD peptide. The cytotoxicity of the multifunctionalized gold nanoclusters was demonstrated through red light irradiation of human lung cancer-derived A549 cells treated with the synthesized nanomaterials. The significant cytotoxicity exhibited by the cells underscores the potential utility of this method in advanced cancer therapies.

Photocatalytic C-H Disulfuration for the Preparation of Indolizine-3-disulfides

A photocatalytic C-H disulfuration of indolizines was developed, giving an approach to a wide variety of indolizine-3-disulfides with good yields. Trisulfide dioxides were explored as a high-efficient disulfuration reagent. This disulfuration reaction could be scaled up to grams. Mechanistic studies support a photoinduced pathway involving the generation of indolizine cationic radicals. A bulky alkyl substituent on terminal sulfur of trisulfide dioxide A was necessary for selective formation of disulfide over monosulfide.

Red light-induced conjugation of amines through amide bond formation triggered via photooxidation of 3-acylindolizines

The development of a conjugation method initiated by irradiation of long-wavelength light (>500 nm) to prepare densely functionalized molecules while avoiding undesired photodegradation has attracted considerable attention. Here we show an amide bond formation method based on the photoreaction of 3-acylindolizines in the presence of amines triggered via red-light irradiation. Photooxidation of 3-acylindolizines using a catalytic amount of a photosensitizer and red light-emitting diodes (660 nm) affords the corresponding conjugated amides in nearly quantitative yields within <5 min. This transformation can be performed in aqueous organic solvents and is applicable to diverse aliphatic amines with various functional groups, including the moieties responsive to short-wavelength light.