Archana Jain

A halogen‐ and metal‐free deep eutectic solvent (DES) consisting of choline hydroxide (ChOH) and urea (1:2) was employed as a green, reusable, and cost‐effective medium for the one‐pot synthesis of amide derivatives from aldehydes and hydroxylamines. The DES served simultaneously as solvent and catalyst, enabling the efficient formation of a wide variety of amides. The protocol afforded biologically and medicinally relevant compounds, including nicotinamide and bebenil, in excellent yields under mild conditions.

Herein, we synthesize and characterize three diprotic hybrid E ^ N ^ N ^ N ^ E (E = BH ₃ , S, Se) amidophosphineborane and chalcogenide multidentate ligands [{Ph ₂ P(E)NHCH ₂ } ₂ C ₅ H ₃ N] (E = BH ₃ ( 1‐H2 ); S ( 2‐H2 ); Se ( 3‐H2 )) and probed their reactions with alkaline earth (Ae) metal amides [Ae{N(SiMe ₃ ) ₂ } ₂ (THF) ₂ ] [Ae = Mg, Ca, Sr] in THF. The Ae metal silylamides smoothly trigger the deprotonation of 1‐H2, 2‐H2 and 3‐H2 , which produce complexes represented by generic notation [κ ⁵ ‐({Ph ₂ P(E)NCH ₂ } ₂ C ₅ H ₃ N)‐Ae(THF) ₂ ]; [E = BH ₃ ; Ae = Mg ( 1a ), Ca ( 1b ), E = S; Ae = Mg ( 2a ), Ca ( 2b ), Sr ( 2c ), and E = Se; Ae = Mg ( 3a ), Ca ( 3b ), Sr ( 3c )] in 90–98% yield with the elimination of volatile [NH(SiMe ₃ ) ₂ ]. Additionally, the barium analogue, 2d , was obtained in good yield by a salt metathesis reaction of the diprotic ligand 2‐H2 , potassium benzyl (KCH ₂ Ph), and barium iodide (BaI ₂ ). Solid state structures of ligands ( 2‐H2, and 3‐H2 ) and metal complexes ( 1a , 1b , 2b , 2c , 3a , and 3b ) reveal that non‐planar coordinating sites of ligands (N, P, E) enforce a co‐planar penta‐coordination to alkaline earth metals (Mg, Ca, Sr). Moreover, the Ae metal complexes exhibited multitasking catalytic activity for the hydroboration of heterocumulenes (e.g., isocyanates and carbodiimides) and the ROP polymerization of cyclic esters ( rac ‐lactide, ε‐caprolactone).

A choline chloride–ethylene glycol-based DES that mediates a green, metal-free, efficient methodology has been described for the synthesis of a series of biologically and pharmaceutically important nitrogen heterocycles.

A unique quaternary diammonium salt and urea (1 : 2)-containing deep eutectic solvent (DES) is introduced as a simple and efficient catalytic medium for the atom-economic synthesis of oxazolidinone compounds from epoxides and isocyanates.

In this report, we describe the synthesis and structural characterization of two zinc alkyl complexes supported by anionic PN-morpholine ligand moieties with the general formula [κ²-{Ph₂P(X)N-(CH₂)₂N(CH₂CH₂)₂O}Zn(C₂H₅)]₂ [X = Se (2a); S (2b)]. Both zinc complexes were fully characterized by ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopy, and single-crystal X-ray diffraction analysis was performed to determine their molecular structures in the solid state. Complexes 2a and 2b have dimeric structures comprising an eight-membered intermolecular-metalacyclic ring adopting the most stable chair form. Furthermore, zinc complex 2a demonstrated exceptional catalytic activity for hydrosilylation of a wide range of aldehydes and ketones under mild reaction conditions. Hydrosilylated derivatives were confirmed by ¹H and ¹³C{¹H} NMR spectroscopy.

In this study, we discuss the synthesis and structural characterization of three N‐heterocyclic carbene isothiocyanate zwitterionic ligands, 1,3‐bis(2,6‐diisopropylphenyl)‐2‐N‐phenyl‐thiocarbamoyl imidazolium (Im^Dipp‐CSNPh, L1), 1,3‐bis(tert‐butyl)‐2‐N‐phenylthiocarbamoyl imidazolium (Im^tBu‐CSNPh, L2) and 1,3‐bis(2,4,6‐trimethylphenyl)‐2‐N‐phenylthiocarbamoyl imidazolium (Im^Mes‐CSNPh, L3) and their cadmium complexes, [(Im^Dipp‐CSNPh)₂CdCl][CdCl₃] (1) and [(Im^tBu‐CSNPh)Cd(μ‐Cl)Cl]₂ (2). Both bench‐stable cadmium complexes were synthesized by directly reacting the corresponding NHC‐CSNPh adducts with anhydrous cadmium chloride. The solid‐state structures of zwitterionic NHC‐isothiocyanate betaine adducts (L1‐L3) and cadmium complexes (1 and 2) were investigated with the assistance of single crystal X‐ray diffraction analysis. A steric modification of N‐substituent on NHC governs a unique structural change from betaine Im^Dipp‐CSNPh coordinated cationic cadmium complex to neutral dimeric cadmium complex with Im^tBu‐CSNPh.

The synthesis, structural characterization, and catalytic application of two novel aluminum complexes, [ κ ³ _ENSe −{Ph ₂ P(E)N−C ₆ H ₄ −SePh}AlMe ₂ ] [E=S ( 1 ) and Se ( 2 )] supported by new pincer‐type phenylselenium‐phosphanamidinate chalcogenide ligands are described. The molecular structures of both complexes in their solid states reveal a distorted trigonal bipyramidal geometry around the Al(III) ion, involving monoanionic ligand {Ph ₂ P(E)N−C ₆ H ₄ −SePh} ⁻ bonded to the AlMe ₂ ‐motif in a tridentate manner. Complex 1 was found to be an effective pre‐catalyst for the cyanosilyation of aldehydes and ketones with TMSCN under solvent‐free conditions. The reaction protocol is simple, efficient, and has a diverse substrate scope of aldehydes and ketones, showing superior functional group tolerance. The kinetic study revealed that ketone reduction proceeded with first‐order dependence on ketone concentrations, TMSCN, and catalyst 1 .

A wide variety of thioamides are obtained in good-to-excellent yields by the reaction of substituted aldehydes/ketones, secondary amines, and elemental sulfur in a choline chloride–urea (1 : 2)-based deep eutectic solvent (DES).