Susmita Mandal

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.

The reaction of two α‐diimine ligands, N , N‐ disubstituted 1,4‐diaza‐butadienes ( ^Dipp DAD and ^{t Bu} DAD) with dineosilylmagnesium [Mg(CH ₂ SiMe ₃ ) ₂ ] directed the migration of mononeosilyl group(─CH ₂ SiMe ₃ ) to one of the two C═N bonds of the diaza ligand, followed by intramolecular hydrogen migration, which resulted in the synthesis of amido‐imino magnesium complexes, [ κ ² ‐{Dipp─N═C(CH ₂ SiMe ₃ )─CH ₂ NDipp}‐Mg(CH ₂ SiMe ₃ ){THF}] ( 1 ) and [ κ ² ‐{ t Bu─N═C(CH ₂ SiMe ₃ )‐CH ₂ N t Bu}Mg(CH ₂ SiMe ₃ )] ₂ ( 2 ), respectively in very good yields. Single‐crystal X‐ray diffraction analysis elucidated the THF‐solvated monomeric structure of complex 1 , whereas magnesium complex 2 crystallized as a dimeric form containing a Mg ₂ N ₂ unit as a four‐membered metallacycle. The magnesium neosilyl complexes 1 and 2 efficiently catalyzed the hydroboration of epoxides and esters in the presence of pinacolborane (HBpin), leading to the regioselective formation of alcohol derivatives and boronate esters, respectively. The hydroboration of several aryl and alkyl epoxides is converted to a selectively Markovnikov product, branched boronate esters instead of linear ones, which, upon hydrolysis, result in secondary alcohols in high yields. Furthermore, complexes 1 and 2 catalyzed the hydroboration of aryl, alkyl, and cyclic esters, resulting in the formation of benzylic and linear boronate esters.‐. Both magnesium complexes and all boronate esters were characterized by multi‐nuclear NMR [ ¹ H, ¹³ C{ ¹ H}, ¹¹ B{ ¹ H}, and ¹ H‐DOSY(for complex 2 )] spectroscopy.

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.

A series of amidinato‐supported magnesium neosilyl complexes with the general formula [Mg(CH₂SiMe₃)‐{RN = C(CH₂SiMe₃)NR}]₂ (R = tBu, 1a; R = Cy, 1b; R = iPr, 1c) were prepared in excellent yields by the insertion of a carbodiimide motif in the magnesium–carbon bond of the magnesium neosilyl complex [Mg(CH₂SiMe₃)₂]. A homoleptic magnesium complex [Mg{tBuN = C(CH₂SiMe₃)NtBu}₂] (2a) was also prepared using [Mg(CH₂SiMe₃)₂] and di‐tert‐butylcarbodiimide in a 1:2 molar ratio in toluene. The molecular structures of all the magnesium complexes 1a–1c and 2a in their solid state were confirmed by single crystal X‐ray diffraction analysis. Further, complexes 1a–1c and 2a were employed as single‐site catalysts for hydrosilylation and hydroboration of alkenes. The magnesium complex 1a exhibited excellent efficiency as a multitasking catalyst under mild conditions for hydrosilylation and hydroboration of alkenes to afford the corresponding organosilane and boronate esters in high yields. Both these atom‐economic reactions demonstrated good functional group tolerance.

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).

Deep eutectic solvent (DES) as an efficient, cost-effective, reusable, and environmentally benign medium for the synthesis of α-aminophosphine oxide/phosphonates from the hydrophosphorylation of aldehydes, amines, and diphenylphosphine oxides/diethylphosphite is reported.

We report catalytic hydroboration of esters as well as nitriles under solvent‐free and mild conditions using single titanium(IV) metal complex, [{κ²‐C₆H₄C(O)N(ⁱPr)C(N‐ⁱPr)=N}{κ³‐(ⁱPr)N=C(O)−C₆H₄−NC(NMe₂)N(ⁱPr)}TiNMe₂] 1 as a sustainable, economical, and efficient pre‐catalyst. The molecular structure of the Ti^IV complex in the solid state reveals the unique coordination of Ti^IV metal with N, N, and O atoms of one quinazolinone unit via in‐situ rearrangement, while another quinazolinone moiety coordinates in bidentate fashion via both N atoms only. The Ti^IV complex demonstrates excellent activity as a pre‐catalyst towards the hydroboration of a wide array of esters and nitriles with pinacolborane (HBpin) to afford alkoxyboranes and diboryl amines in high yield (up to 99 %) with greater tolerance to a variety of electron‐withdrawing and electron‐donating functional groups. A most plausible mechanism of hydroboration of esters is also proposed based on kinetics and NMR studies, which suggests the formation of titanium‐hydride species as an active catalyst.