Photolytic ortho-Selective Amino Pyridylation of Aryl Isocyanates with N-Amino Pyridinium Ylides for the Synthesis of N-Arylsulfonyl Ureas.

Herein, we report an expedient synthesis of aryl sulfonyl ureas 4 and 5 from N-amino pyridinium ylides and aryl isocyanates. N-Aminopyridinium ylides 3 are synthesized via blue light-emitting diode irradiation of pyridine/isoquinoline and appropriate iminoiodinanes. The strategy involved a hitherto unknown carboamination of imine moieties (of aryl isocyanates) via a three-component reaction of pyridine derivatives/isoquinoline 1, N-aryl sulfonyl iminoiodinanes 2, and numerous aryl isocyanates at room temperature in 2-methyl tetrahydrofuran to afford the target compounds in moderate to excellent yields. N-Arylpyridinium ylides 3 (as intermediates) undergo a [3+2] cycloaddition with the aryl isocyanates followed by the aromatization of the pyridine/isoquinoline moiety to afford compounds 4. On the basis of the substitution pattern among the reactants, in some cases pyridine extrusion occurs during the reaction to afford depyridinylated aryl sulfonyl ureas 5. In general, isocyanates are used as dipolarophiles in [3+2] cycloaddition reactions. However, regioselective amino pyridylation of these species is a first. Control experiments and density functional theory calculations elucidate the reaction mechanism. The batch process of the protocol could be seamlessly transferred to the photoflow synthesis.

Protocol for aqueous synthesis of bioactive quaternary ammonium betaine derivatives under blue LED.

Quaternary ammonium compounds exhibit diverse applications as antibiotics, as surfactants, in paper industries, in sewage treatment, and in aquaculture. Here, we present a protocol for synthesizing a library of bioactive quaternary ammonium betaine derivatives under blue LED in water. We describe steps for preparing diazo compounds, synthesizing glycine betaine derivatives, and isolating pure final compounds via precipitation from an aqueous reaction mixture. This protocol promotes a sustainable approach by using water as the reaction medium and room temperature reactions. For complete details on the use and execution of this protocol, please refer to Rath et al. (2023).1.

Metal-free synthesis and study of glycine betaine derivatives in water for antimicrobial and anticancer applications.

A sustainable synthesis of interesting glycine betaine derivatives from cyclic 3°-amines viz. N-methyl morpholine (NMM), N-methyl piperidine (NMP), and 1,4-diazabicyclo[2.2.2]octane (DABCO) with numerous aryl diazoacetates 1 in water and under blue LED is reported. Generally, 3°-amines and metal carbenoids (from diazoacetates with transition metal catalysts) provide C-H insertion at the α-position of the amines. Computational comparison of the metal carbenoid with the singlet carbene (metal free and generated under blue LED) realized the difference in reactivity. Next, experimental results corroborated the preliminary findings. The products were isolated either by precipitation of the solid or gel-like final products from the aqueous reaction mixture without any chromatographic purification. The reaction mechanism was realized by control experiments. These compounds exhibit selective bactericidal properties against Gram-positive S. aureus, induce lipid droplets (LDs) formation in HePG2 cells and single crystal X-ray diffraction study of their halogenated analogs reveal interesting Hal … Hal contacts.

"All-Aqueous" Tandem Boc-Deprotection and Alkylation of N-Bocbenzimidazole Derivatives under Visible Light with Alkyl Aryl Diazoacetates: Application to Site-Selective Insertion of Carbenes into the N-H Bond of Purines.

Herein, we have reported a blue LED-induced tandem Boc-deprotection and NH-alkylation of benzimidazole derivatives with methyl aryl diazoacetates. The reactions occur in water at room temperature. The desired products are obtained in good to excellent yields. The putative mechanism of this reaction is discussed based on control experiments and supported by DFT studies. Additionally, the strategy is used to alkylate various purine derivatives via site-selective N1-alkylation to generate acyclic nucleoside analogues.