@article {49381, title = {Unravelling the prebiotic origins of the simplest α-ketoacids in cometary ices: a computational investigation}, journal = {CHEMICAL COMMUNICATIONS}, volume = {60}, year = {2024}, month = {OCT }, pages = {11283-11286}, type = {Journal Article}, keywords = {GLYOXYLATE, Hydrocarbons, Metabolism, Precursors}, issn = {1359-7345}, doi = {10.1039/d4cc03074e}, author = {Dash, Soumya Ranjan and Pandya, Rinu and Singh, Geetika and Sharma, Himanshu and Das, Tamal and Haldar, Hritwik and Hotha, Srinivas and Vanka, Kumar} } @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.} } @article {49507, title = {Studies on the stereoselective synthesis of sacubitril via a chiral amine transfer approach}, journal = {Chemistry-An Asian Journal}, volume = {20}, year = {2025}, month = {MAR }, type = {Article}, abstract = {

We present a comprehensive account of our efforts directed towards the synthesis of sacubitril, a neprilysin inhibitor used in combination with valsartan and marketed as Entresto (TM). Our initial approach to the formal synthesis of sacubitril employed a chiral pool strategy, utilizing (S)-pyroglutamic acid as a key building block and Cu(I)-mediated Csp2-Csp3 cross-coupling as a key transformation. Further investigations led to the development of chiral amine transfer (CAT) reagents-based stereoselective synthesis. This involved the E-selective construction of gamma-ylidene-butenolide from readily available biphenyl bromide and 4-pentynoic acid, the conversion of this butenolide to its ene-lactam using chiral amine, and substrate-controlled diastereoselective reduction of ene-lactam using Et3SiH or Pd/C, H2 (overall chiral amine transfer) as key transformations. Antipodal lactam intermediates were synthesized using corresponding chiral amines, and the stereochemical outcomes during the ene-lactam reduction with Et3SiH were rationalized by DFT studies.

}, keywords = {Chiral Amine Transfer (CAT) approach, Chiral pool approach, Sacubitril, stereoselective synthesis}, issn = {1861-4728}, doi = {10.1002/asia.202401223}, author = {Sadanande, Megha V. and Thorat, Sagar S. and Sharma, Himanshu and Singh, Geetika and Vanka, Kumar and Gonnade, Rajesh G. and Kontham, Ravindar} } @article {49960, title = {(NHC-olefin)-nickel(0) nanoparticles: an efficient and selective catalyst for hydrogenation reactions at low temperature and pressure}, journal = {Journal of Catalysis}, volume = {453}, year = {2026}, month = {JAN}, pages = {116487}, type = {Article}, abstract = {

The reduction of a NHC-cinnamyl nickel(II) organometallic complex through the use of different MeMgBr or MeMgCl reagents led to two types of NHC-olefin-coordinated nickel nanoparticles. Both of these unsupported nickel-NHC based nanomaterials behaved under hydrogen pressure as effective and selective catalysts operating at low temperature (\<= 80 degrees C), pressure (\<= 20 bar) and loading (\<= 6 mol\%) for the reductions of broad scopes of alkenes, alkynes, imines and heterocycles, including a challenging tetra-substituted alkene. Among these two nickel-NHC nanocatalysts, the one generated with MeMgCl showed a significant high catalytic activity with high yields and could stand the comparison with Raney nickel and state-of-the-art nickel nanocatalysts. For example, by studying the hydrogenation of 1-phenylcyclohexene in ethanol at 60 degrees C under 10 bar of H2, 3 mol\% of this catalyst achieved the reaction within a single hour on a 5 mmol/0.8 g substrate scale with a yield of 96 \%, a turnover number (TON) of 32 and a turnover frequency (TOF) of 32. Characterizations confirmed the coordination of the NHC-olefin ligands to the nickel nanoparticles, the reduced state of the nickel and the (poly-) crystallinity of the nanoparticles.

}, keywords = {alkenes, Alkynes, heterocycles, Hydrogenation, imines, N -heterocyclic carbene ligand, nanocatalysis, Nickel}, issn = {0021-9517}, doi = {10.1016/j.jcat.2025.116487}, author = {Avello, Marta G. and Singh, Geetika and Truong-Phuoc, Lai and Vidal, Loic and Papaefthimiou, Vasiliki and Chesse, Matthieu and Gruber, Nathalie and Chetcuti, Michael J. and Vanka, Kumar and Ritleng, Vincent and Pham-Huu, Cuong and Michon, Christophe} }