01170nas a2200157 4500008004100000245012800041210006900169260000800238300001200246490000800258520053900266100002000805700003100825700003100856856012500887 2006 eng d00aSuzuki cross-coupling reactions catalyzed by palladium complex of an inexpensive phosphinite, 2-diphenylphosphinoxynaphthyl0 aSuzuki crosscoupling reactions catalyzed by palladium complex of cNOV a78–830 v2593 a

A facile and less expensive monophosphinite ligand 2-(diphenylphosphinoxy)-naphthyl, C10H7OPPh2 (1) has been synthesized from the reaction of β-naphthol with chlorodiphenylphosphine. The mixture of Pd(OAc)2 and 1 catalyzes the Suzuki cross-coupling of a variety of aryl halides with aryl boronic acids at room temperature or at 60 °C, giving generally high yields even under low catalytic loads. The effect of solvent, base and catalyst loading on the coupling reaction of aryl halide with arylboronic acid is also described.

1 aPunji, Benudhar1 aGanesamoorthy, Chelladurai1 aBalakrishna, Maravanji, S. uhttps://library.ncl.res.in/content/suzuki-cross-coupling-reactions-catalyzed-palladium-complex-inexpensive-phosphinite-202233nas a2200157 4500008004100000245022000041210006900261260000800330300001600338490000700354520152100361100002001882700002001902700003101922856012201953 2006 eng d00aSynthesis of neutral (PdII, PtII), Cationic (PdII), and water-induced anionic (PdII) complexes containing new mesocyclic thioether-aminophosphonite ligands and their application in the suzuki cross-coupling reaction0 aSynthesis of neutral PdII PtII Cationic PdII and waterinduced an cOCT a9454–94640 v453 a

Mesocyclic thioether−aminophosphonite ligands, {−OC10H6(μ-S)C10H6O−}PNC4H8O (2a, 4-(dinaphtho[2,1-d:1‘,2‘-g][1,3,6,2]dioxathiaphosphocin-4-yl)morpholine) and {−OC10H6(μ-S)C10H6O−}PNC4H8NCH3 (2b, 1-(dinaphtho[2,1-d:1‘,2‘-g][1,3,6,2]dioxathiaphosphocin-4-yl)-4-methylpiperazine) are obtained by reacting {−OC10H6(μ-S)C10H6O−}PCl (1) with corresponding nucleophiles. The ligands 2a and 2b react with (PhCN)2PdCl2 or M(COD)Cl2 (M = PdII or PtII) to afford P-coordinated cis-complexes, [{(−OC10H6(μ-S)C10H6O−)PNC4H8X-κP}2MCl2] (3a, M = PdII, X = O; 3b, M = PdII, X = NMe; 4a, M = PtII, X = O; 4b, M = PtII, X = NMe). Compounds 2a and 2b, upon treatment with [Pd(η3-C3H5)Cl]2 in the presence of AgOTf, produce the P,S-chelated cationic complexes, [{(−OC10H6(μ-S)C10H6O−)PNC4H8X-κP,κS}Pd(η3-C3H5)](CF3SO3) (5a, X = O and 5b, X = NMe). Treatment of 2a and 2b with (PhCN)2PdCl2 in the presence of trace amount of H2O affords P,S-chelated anionic complexes, [{(−OC10H6(μ-S)C10H6O−)P(O)-κP,κS}PdCl2](H2NC4H8X) (6a, X = O and 6b, X = NMe), via P−N bond cleavage. The crystal structures of compounds 1, 2a, 2b, 4a, and 6a are reported. Compound 6a is a rare example of crystallographically characterized anionic transition metal complex containing a thioether−phosphonate ligand. Most of these palladium complexes proved to be very active catalysts for the Suzuki−Miyaura reaction with excellent turnover number ((TON), up to 9.2 × 104 using complex 6a as a catalyst).

1 aPunji, Benudhar1 aMague, Joel, T.1 aBalakrishna, Maravanji, S. uhttps://library.ncl.res.in/content/synthesis-neutral-pdii-ptii-cationic-pdii-and-water-induced-anionic-pdii-complexes01891nas a2200169 4500008004100000245015900041210006900200260000800269300001600277490000700293520120300300100002101503700002201524700002401546700002001570856013101590 2016 eng d00aSynthesis of quinoline-based NNN-pincer nickel(II) complexes: a robust and improved catalyst system for C–H bond alkylation of azoles with alkyl halides0 aSynthesis of quinolinebased NNNpincer nickelII complexes a robus cMAY a1785–17930 v353 a

The quinoline-based pincer nickel(II) complexes κN,κN,κN-{R2N-C6H4-(μ-N)-C9H6N}NiX ((R2NNNQ)NiCl: R = Me, 2a; R = Et, 2b) were synthesized by the reaction of the ligand precursors (R2NNNQ)H (R = Me, 1a; R = Et, 1b) with (DME)NiCl2 in the presence of Et3N. Similarly, the pincer nickel(II) derivatives (R2NNNQ)NiX (R = Me, X = Br, 3a; R = Et, X = Br, 3b; R = Me, X = OAc, 4a) were obtained by treatment of the ligands (R2NNNQ)H with the nickel precursor (THF)2NiBr2 or Ni(OAc)2. All of these complexes were characterized by 1H and 13C NMR spectroscopy as well as by elemental analysis. Further, the molecular structures of 2a and 3a,b were elucidated by X-ray crystallography. Complex 2a is found to be an efficient catalyst for the direct C–H bond alkylation of substituted benzothiazoles and oxazoles with various unactivated alkyl halides containing β-hydrogens under mild reaction conditions. The catalyst 2a is very robust and was recycled and reused five times for the alkylation reaction without a decrease in its catalytic activity. Preliminary studies reveal that the catalyst 2a acts as an active catalyst and the alkylation reaction appears to operate via a radical pathway.

1 aPatel, Ulhas, N.1 aPandey, Dilip, K.1 aGonnade, Rajesh, G.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/synthesis-quinoline-based-nnn-pincer-nickelii-complexes-robust-and-improved-catalyst-system02018nas a2200169 4500008004100000022001400041245017500055210006900230260000800299300001600307490000700323520132100330100002701651700002401678700002001702856012601722 2018 eng d a1477-922600aSynthesis of quinolinyl based pincer copper (II) complexes: an efficient catalyst system for Kumada coupling of alkyl chlorides and bromides with alkyl Grignard reagents 0 aSynthesis of quinolinyl based pincer copper II complexes an effi cDEC a16747-167540 v473 a

Quinolinamide-based pincer copper(ii) complexes, (N),(N),(N)-{C9H6N-(-N)-C(O)CH2NEt2}CuX [((NNN2Et)-N-Q)CuX (X = Cl, 2; X = Br, 3; X = OAc, 4)], were synthesized by the reaction of ligand ((NNN2Et)-N-Q)-H (1) with CuX2 (X = Cl, Br or OAc) in the presence of Et3N. The reaction of ((NNN2Et)-N-Q)-H with CuX (X = Cl, Br or OAc) also afforded the Cu(ii) complexes 2, 3 and 4, respectively, instead of the expected Cu(i) pincer complexes. The formation of Cu(ii) complexes from Cu(i) precursors most likely occurred via the disproportionation reaction of Cu(i) into Cu(0) and Cu(ii). A cationic complex [((NNN2Et)-N-Q)Cu(CH3CN)]OTf (5) was synthesized by the treatment of neutral complex 2 with AgOTf. On the other hand, the reaction of ((NNN2Et)-N-Q)-H (1) with [Cu(MeCN)(4)]ClO4 produced cationic Cu(i) complex, [((NN)-N-Q(H)N-2(Et))Cu(CH3CN)]ClO4 (6), in good yield. All complexes 2-5 were characterized by elemental analysis and HRMS measurements. Furthermore, the molecular structures of 2, 3 and 4 were elucidated by X-ray crystallography. Complex 4 crystallizes in a dimeric and catemeric pattern. The cationic complex 5 was found to be an efficient catalyst for the Kumada coupling reaction of diverse nonactivated alkyl chlorides and bromides with alkyl magnesium chloride under mild reaction conditions.

1 aPandiri, Hanumanprasad1 aGonnade, Rajesh, G.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/synthesis-quinolinyl-based-pincer-copper-ii-complexes-efficient-catalyst-system-kumada01578nas a2200169 4500008004100000022001400041245012400055210006900179260000900248300001400257490000700271520093500278100002101213700002201234700002001256856013201276 2019 eng d a0276-733300aScope and mechanistic aspect of nickel-catalyzed alkenylation of benzothiazoles and related azoles with styryl bromides0 aScope and mechanistic aspect of nickelcatalyzed alkenylation of  cJUN  a2422-24300 v383 a

Alkenylation of benzothiazoles and related azoles with alkenyl bromides is achieved employing the well-defined and air-stable nickel complexes, (bpy)NiBr2 and [Ni(bpy)(3)] [NiBr4], as catalysts. Numerous electronically distinct alkenyl bromides efficiently coupled with substituted benzothiazoles, oxazoles, and benzimidazoles under the catalytic conditions to afford 2-alkenylated azoles. An extensive mechanistic study of the alkenylation of benzothiazole using (bpy)NiBr2 highlights a single-electron transfer process for the reaction involving the two-step one-electron oxidative addition of alkenyl bromide. The substrate benzothiazole plays a significant and diverse role in the reaction, and C-H bond cleavage is reversible in nature. Detailed kinetic analysis and control reactivity studies are indicative of a Ni(I)/Ni(III) pathway for the alkenylation comprising the rate-influencing reductive elimination step.

1 aPatel, Ulhas, N.1 aJagtap, Rahul, A.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/scope-and-mechanistic-aspect-nickel-catalyzed-alkenylation-benzothiazoles-and-related-azoles01222nas a2200145 4500008004100000245009300041210006900134260000800203300001400211490000800225520068500233100002300918700002000941856011500961 2019 eng d00aSelective synthesis of secondary amines from nitriles by a user-friendly cobalt catalyst0 aSelective synthesis of secondary amines from nitriles by a userf cSEP a3930-39360 v3613 a

Selective hydrogenation/reductive amination of nitriles to secondary amines catalyzed by an inexpensive and user-friendly cobalt complex, (Xantphos)CoCl2, is reported. The use of (Xantphos)CoCl2 and ammonia borane (NH3-BH3) combination affords the selective reduction of nitriles to symmetrical secondary amines, whereas the employment of (Xantphos)CoCl2 and dimethylamine borane (Me2NH-BH3) along with external amines produce unsymmetrical secondary amines and tertiary amines. The general applicability of this methodology is demonstrated by the synthesis of 43 symmetrical and unsymmetrical secondary and tertiary amines bearing diverse functionalities.
 

1 aSharma, Dipesh, M.1 aPunji, Benudhar uhttps://library.ncl.res.in/content/selective-synthesis-secondary-amines-nitriles-user-friendly-cobalt-catalyst02238nas a2200193 4500008004100000022001400041245013300055210006900188260000800257300001400265490000700279520150900286100002201795700002001817700002901837700002601866700002001892856013201912 2025 eng d a2044-475300asyn-Selective hydrosilylation and hydroboration of alkynes at room temperature catalyzed by a phosphine-free (NNN)Fe(ii) complex0 asynSelective hydrosilylation and hydroboration of alkynes at roo cNOV a6716-67250 v153 a

Catalytic hydrofunctionalization of alkynes is the ideal and atom-economical route to synthesize vinylsilanes and vinylboronates, which are valuable organic building blocks. However, the process suffers from using expensive phosphine-ligated catalysts, sensitive organometallic activators, and elevated reaction temperatures. To overcome these challenges, herein, we developed a series of phosphine-free (NNN)-ligated iron complexes and demonstrated their potential as efficient catalysts for the hydrosilylation and hydroboration of both internal and terminal alkynes using NaOtBu as an activator. The reactions proceeded smoothly using 1.5 mol% catalyst loading at room temperature and provided syn-selective vinylsilanes and vinylboronates. This hydrofunctionalization exclusively delivered mono-silylated and mono-borylated vinyls with tolerance of sensitive functionalities. At the same time, terminal alkynes provided excellent anti-Markovnikov selectivity with thermodynamically feasible beta-(E)-vinylsilanes and beta-(E)-vinylboronates. The presence of an N-H moiety in the ligand backbone is crucial in generating an Fe(ii) active catalyst and facilitating the catalytic process. Mechanistic investigations, including controlled reactions and external additive experiments, were performed to propose a redox-neutral reaction mechanism with iron maintaining its +2 oxidation state throughout the cycle. The DFT energy calculations unanimously support the proposed reaction mechanism.

1 aPradhan, Chandini1 aDubey, Shivansh1 aSamal, Pragnya, Paramita1 aKrishnamurty, Sailaja1 aPunji, Benudhar uhttps://library.ncl.res.in/content/syn-selective-hydrosilylation-and-hydroboration-alkynes-room-temperature-catalyzed-phosphine