02325nas a2200241   4500008004100000022001400041245010100055210006900156260006900225300001000294490000800304520143300312653001201745653003401757653002301791653003901814653001201853653002201865100001801887700002501905700002401930856012901954       2014                        eng d  a0010-854500aContemporary avenues in catalytic P-H bond addition reaction: a case study of hydrophosphination0 aContemporary avenues in catalytic PH bond addition reaction a ca  aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcAPR  a52-730 v2653 a<p>Remarkable advances and current state-of-the-art developments in catalytic hydrophosphination of alkenes and alkynes are reviewed. The challenges in constructing a C P bond with a special emphasis on metal catalysed (asymmetric) hydrophosphination are highlighted. Only those systems that unambiguously proceed via P H bond addition across a C-C/X (X = O, N, S) multiple bond have been covered in this overview. Reviewed examples support the assumption that either strongly chelating ligands or reaction products that act as ligands, enhance the rate of hydrophosphination. The asymmetric variant of this transformation allows installation of p-chiral [enantiomeric excess (ee) up to 82%] as well as C-chiral (ee up to 99%) centres. The limited spectroscopic, mechanistic data and OFT calculations point at two distinctly different mechanisms. In case of hydrophosphination, the metal undergoes oxidative addition and reductive elimination steps (in general), thus changing the oxidation state from M(0) to M(II) and back to M(0). Whereas in asymmetric hydrophosphination it is proposed that the oxidation state of the metal remains unaltered throughout the catalytic cycle. The examples described in this overview showcase the real power of catalytic hydrophosphination in constructing various phosphorus compounds, which may initiate a new era in organo-phosphorus chemistry. (C) 2014 Elsevier B.V. All rights reserved.</p>10aAlkynes10aAsymmetric hydrophosphination10aHydrophosphination10aMetal catalyzed hydrophosphination10aOlefins10aP-H bond addition1 aKoshti, Vijay1 aGaikwad, Shahaji, R.1 aChikkali, Samir, H.  uhttps://library.ncl.res.in/content/contemporary-avenues-catalytic-p-h-bond-addition-reaction-case-study-hydrophosphination-002478nas a2200193   4500008004100000022001400041245012500055210006900180260000900249300001400258490000700272520177700279100002102056700002502077700000502102700002402107700002402131856012902155       2021                        eng d  a1477-922600aControlled di-lithiation enabled synthesis of phosphine-sulfonamide ligands and implications in ethylene oligomerization0 aControlled dilithiation enabled synthesis of phosphinesulfonamid  cMAR   a3717-37230 v503 a<p>Catalyst design for ethylene oligomerization has attracted significant interest. Herein, we report the synthesis of phosphine-sulfonamide-derived palladium complexes and examine their performance in ethylene oligomerization. Arresting a dilithiation intermediate of N-(2-bromophenyl)-4-methylbenzenesulfonamide (1) at -84 degrees C selectively produced N-(2-(bis(2-methoxyphenyl)phosphanyl)phenyl)-4-methylbenzenesulfonamide (L1A). However, the same reaction at -41 degrees C delivered a different ligand; 2-(bis(2-methoxyphenyl)phosphanyl)-4-methyl-N-phenylbenzenesulfonamide (L2A). The generality of our strategy has been demonstrated by preparing N-(2-(diphenylphosphanyl)phenyl)-4-methylbenzenesulfonamide (L1B) and 2-(diphenylphosphanyl)-4-methyl-N-phenylbenzenesulfonamide (L2B). Subsequently, L1A and L1B were treated with a palladium precursor to yield 5-membered complexes C1 and C2, respectively. In contrast, L2A upon treatment with palladium produced a 6-membered metal complex C3. Thus, a small library of 7 palladium complexes (C1-C7) were synthesized by varying the donor moiety (pyridine, DMSO, and acetonitrile). The identity of palladium complexes was unambiguously ascertained using a combination of spectroscopic and analytical methods, including single-crystal X-ray diffraction. The performance of the complexes C1-C7 was investigated in ethylene oligomerization and almost all of them were found to be active. The resultant ethylene oligomers were characterized using H-1 and C-13 NMR, MALDI-ToF-MS, and GPC. Detailed screening of reaction parameters revealed 100 degrees C and 40 bars ethylene to be optimal conditions. Complex C5 outperformed other complexes and produced ethylene oligomers with a molecular weight of 1000-1900 g mol(-1).</p>
1 aMote, Nilesh, R.1 aGaikwad, Shahaji, R.1 a1 aGonnade, Rajesh, G.1 aChikkali, Samir, H.  uhttps://library.ncl.res.in/content/controlled-di-lithiation-enabled-synthesis-phosphine-sulfonamide-ligands-and-implications