Tarun Kanti Panda

We report a ruthenium-catalyzed regioselective and stereospecific hydrostannation of terminal alkynes in a switchable solvent system under ambient conditions. This method exhibits excellent selectivity and functional group tolerance, enabling controlled Markovnikov and anti-Markovnikov addition of tributyl tin hydride to the C(sp)–C(sp) bond. The stereospecific formation of (E)-β-vinylstannane from (Z)-β-vinylstannane by isomerization at high temperatures was verified through a detailed NMR study. We also demonstrated the utility of this method by synthesizing an organotin-containing boronic ester that can be used for sequential cross-coupling reactions as a nucleophilic partner.

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.

A zinc complex bearing imino‐phosphanamidinate chalcogenide ligands efficiently promotes the ring‐opening polymerization (ROP) of rac ‐lactide ( rac ‐LA) and ε‐caprolactone (ε‐CL), as well as their copolymerization. The complex demonstrated good control over the ROP of rac ‐LA, affording isotactic poly (lactic acid) (PLA) with high stereoselectivity ( P _m = 0.82) and narrow dispersity (Ð < 1.3). One‐pot ring‐opening copolymerization (ROCOP) of rac ‐LA and ε‐CL in the presence of the zinc complex has been shown to produce random copolymers with predictable molecular weights. The fact that the randomization of the copolymers is driven concurrently by the formation of a gradient/partially random copolymer species and slow transesterification was established via in situ NMR spectroscopy. PLA‐ co ‐CL copolymers with varying CL/LA ratios were synthesized, displaying a single glass transition temperature ( T _g ) within the range between the T _g values of the corresponding homopolymers.

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.

This study explores the coordination chemistry and catalytic behavior of cesium‐based multinuclear complexes supported by bis(diphenylphosphino)chalcogenide ligands {CH ₂ (P(E)Ph ₂ ) ₂ } [where E = S ( 1 ) and Se ( 2 )] in the ROP of cyclic esters. By reacting {CH ₂ (P(E)Ph ₂ ) ₂ } with cesium amide [Cs{N(SiMe ₃ ) ₂ }], we isolated two distinct structural motifs: a one‐dimensional coordination polymer [CH{PPh ₂ S} ₂ Cs] _∞ ( 3 ) and a dimeric complex [CH{PPh ₂ Se} ₂ Cs] ₂ ( 4 ). Furthermore, the intervention of 18‐crown‐6 in 1D polymeric ladder ( 3 ) commands the formation of contact pair [{18C6}Cs{CH(Ph ₂ PS) ₂ }] ( 5 ), whereas dimeric complex ( 4 ) leads to ion‐separated cesium complex [(18C6) ₂ Cs] ⁺ [CH(PPh ₂ Se) ₂ ] ⁻ ( 6 ). This is one of the rare reports on the structural characterization of a discrete cesium molecular complex featuring a direct Cs–Se interaction, while only ionic solids were known. Complex 6 is the first ion‐pair to display the [HC(PPh ₂ Se) ₂ ] ⁻ anion in its unbound state, which has predominantly been observed in coordinated form with various metals. All complexes were characterized in solution by spectroscopic analysis ( ¹ H and ³¹ P{ ¹ H} NMR), and their solid‐state structures were confirmed by single‐crystal X‐ray diffraction analysis. Notably, the coordination polymer exhibited superior activity in ROP of rac ‐lactide and caprolactone compared to its dimeric or monomeric analog, suggesting a key role for extended metal–ligand cooperativity.

In the present article, we report the synthesis of magnesium, calcium, and zinc complexes derived from the selenoether ligand {Ph ₂ P(S)NH–C ₆ H ₄ –SePh} ( 1 ). The deprotonation of ligand 1 utilizing metal silylamides M{N(SiMe ₃ ) ₂ } ₂ (M = Mg, Ca, and Zn) conducted in tetrahydrofuran (THF) employing a 2:1 molar proportion of ligand‐to‐metal enables the synthesis of their respective complexes, namely [{ κ ² _{N, S} (Ph ₂ P(S)N–C ₆ H _4 SePh)}{ κ ³ _{N, S, Se} (Ph ₂ P(S)N–C ₆ H _4 SePh)}Mg–(THF)] ( 1a ), [{Ph ₂ P(S)N–C ₆ H _4 SePh} ₂ Ca]( 1b ), and [ κ ² _{N, Se} {Ph ₂ P(S)N–C ₆ H _4 SePh} ₂ Zn] ( 1c ) in excellent yield proceeded via elimination of hexamethyldisilazane [HN(SiMe ₃ ) ₂ ]. Single crystal X‐ray diffraction analysis unambiguously revealed that ligand 1 exhibits three distinct coordination modes, κ ‐( N , S ), κ ‐( N , Se ), and κ‐( N , S , Se ), toward the metal centers. This coordination flexibility leads to a distorted octahedral geometry around the magnesium ion in complex 1a , whereas the zinc center in complex 1c adopts a distorted tetrahedral geometry in the solid state. In solution, the complexes were comprehensively characterized by multinuclear NMR spectroscopy ( ¹ H, ¹³ C{ ¹ H}, and ³¹ P{ ¹ H}). Collectively, these findings expand the structural and spectroscopic understanding of closed‐shell metal complexes and highlight the versatility of the selenoether ligand in accessing structurally well‐defined coordination environments.

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).

Herein, we report an efficient approach for synthesizing β-keto trifluoromethyl sulfone through direct conversion from terminal alkynes via hydration using bench-stable zinc complexes (1a-1c). The synthesis of three zinc complexes (1a-1c) supported by imino pyridine morpholine-based ligands is described. Furthermore, this protocol has been successfully integrated into the conversion of valuable isoxazole triflones and heterocyclic compounds.

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.