@article {46834, title = {Highly efficient chemoselective N-tert butoxycarbonylation of aliphatic/aromatic/heterocyclic amines using diphenylglycoluril as organocatalyst}, journal = {Tetrahedron}, volume = {76}, year = {2020}, month = {JUN }, pages = {131223}, type = {Article}, abstract = {

An efficient approach for the Chemoselective N-tert-butoxycarbonylation of a variety of amines using diphenylglycoluril as organocatalyst has been described. For the first time, a plausible mechanism for the N-tert-butoxycarbonylation has been proposed using density functional theory (DFT) calculations supported by NMR studies. The reusability of the organocatalyst and observation of the desired N-Boc protected amines being formed without the formation of side products like urea, oxazolidinone, isocyanate, and N, N-di-Boc derivatives makes the present protocol desirable. (C) 2020 Elsevier Ltd. All rights reserved.

}, keywords = {DFT studies, Diphenylglycouril, N-tert butoxycarbonylation, organocatalyst, Proton shuttle mechanism}, issn = {0040-4020}, doi = {10.1016/j.tet.2020.131223}, author = {Awasthi, Amardeep and Mukherjee, Anagh and Singh, Mandeep and Rathee, Garima and Vanka, Kumar and Chandra, Ramesh} } @article {48791, title = {H-atom site exchange in an iridium trans-dihydrogen/hydride complex, trans-[Ir(H)(?2-H2)(iPr)4(POCOP)(DMAP)]+}, journal = {Dalton Transactions}, volume = {52}, year = {2023}, month = {OCT }, pages = {13858-13863}, type = {Article}, abstract = {

Treatment of trans-[Ir(H)(N)(2)((iPr)4)(POCOP)(DMAP)][BAr4f] (2) with H-2 (1 bar) under ambient conditions (298 K) results in the formation of a trans-[Ir(H)(?(2)-H-2)((iPr)4)(POCOP)(DMAP)][BAr4f] (3) complex. Complex 3 exhibits H-atom site exchange between the bound H-2 and the hydride ligands which are mutually trans to one another. A plausible mechanism of this exchange involves metal-ligand cooperativity as studied by computations.

}, issn = {1477-9226}, doi = {10.1039/d3dt02366d}, author = {Agrawal, Nisha K. and Gayathridevi, S. and Dash, Soumya R. and Vanka, Kumar and Jagirdar, Balaji R.} } @article {50004, title = {Heterolytic cleavage of the B{\textendash}H bond in H3B{\textperiodcentered}L (L = THF, NMe2H) by an electrophilic Ir(iii) pincer complex [Ir(H)(PMe3)(tBu4POCOP)][BAr F4]}, volume = {55}, year = {2025}, month = {NOV}, pages = {476-491}, type = {Article}, abstract = {
Six- and five-coordinate iridium complexes, [Ir(H)Cl(PMe3)(tBu4POCOP)] (2) (tBu4POCOP = κ3-C6H3-2,6-(OPtBu2)2) and [Ir(H)(PMe3)(tBu4POCOP)][BArF4] (3), respectively, have been synthesized and characterized. The reactivity of the electrophilic 16-electron iridium(III) complex\ 3\ with H2, H3B{\textperiodcentered}THF, H3B{\textperiodcentered}NMe2H, and H3B{\textperiodcentered}NMe3\ was investigated. The reaction of complex\ 3\ with H2\ resulted in the formation of\ trans-[Ir(H)(η2-H2)(PMe3)(tBu4POCOP)][BArF4] complex\ 5. Complex\ 3\ was found to activate the B{\textendash}H bonds in H3B{\textperiodcentered}THF and H3B{\textperiodcentered}NMe2H (DMAB) in a heterolytic fashion. The reaction of complex\ 3\ with H3B{\textperiodcentered}THF at 298 K afforded\ trans-[Ir(H)2PMe3(tBu4POCOP)] complex\ 6\ and a boronium compound, [H2B(THF)2][BArF4]. Monitoring the reaction from 179 to 298 K by NMR spectroscopy revealed the formation of a σ-borane intermediate,\ trans-[Ir(H)(η1-HBH2{\textperiodcentered}THF)PMe3(tBu4POCOP)][BArF4] (3a-Int),\ en route\ to the final products observed at 298 K. The formation of this intermediate species was also investigated by density functional theory (DFT) calculations. The reaction of complex\ 3\ with H3B{\textperiodcentered}NMe2H at 298 K yielded a mixture of complexes\ 3\ and\ 5\ and a cyclic diborazane [H2BNMe2]2. The reaction was found to proceed\ via\ intermediates, a σ-borane complex,\ trans-[Ir(H)(η1-HBH2{\textperiodcentered}NMe2H)PMe3(tBu4POCOP)][BArF4] (3b), complex\ 6, [(NHMe2)2BH2][BArF4], and H2B[double bond, length as m-dash]NMe2. Complex\ 3\ exhibited no reactivity with H3B{\textperiodcentered}NMe3.

}, doi = {DOI https://doi.org/10.1039/D5DT01780G}, author = {Pradhan, Mitarani and Surati, Zeel Y. and Pal, Apurba Kumar and Vanka, Kumar and Jagirdar, Balaji R.} } @article {49807, title = {Hypersilylsilylene-supported Ni(0) toluene and Ni(II) complexes with catalytic application}, journal = {Organometallics}, volume = {44}, year = {2025}, month = {NOV}, pages = {2646-2653}, type = {Article}, abstract = {

The reaction of Ni(COD)2 with [PhC(NtBu)2SiSi(SiMe3)3] (1) in toluene results in the formation of an 18-electron silylene-Ni(0) toluene complex (2). The analogous reaction with 1,3-DFB instead of toluene affords the C-H activation followed by ring walking leading to the allylic cyclooctene adduct, the (eta 3-C8H13)Ni(II) complex (3). DFT calculations were carried out to elucidate the mechanism as well as to gain insight into why 1,3-DFB undergoes C-H bond activation instead of C-F bond activation. The use of NiCl2DME permits access to 16-electron (tetrylene)2NiCl2 (Si(4) and Ge(5)) species, and 4 was later used as a catalyst for the C-N coupling reaction.

}, issn = {0276-7333}, doi = {10.1021/acs.organomet.5c00303}, author = {Ajithkumar, V. S. and Bisai, Milan Kumar and Ghanwat, Pratiksha B. and Raj, K. Vipin and Singh, Geetika and Vanka, Kumar and Sen, Sakya S.} }