@article { ISI:000336942100020, title = {Investigation of C-C bond formation mediated by bombyx mori silk fibroin materials}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {2}, number = {6}, year = {2014}, month = {JUN}, pages = {1510-1517}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The formation of C-C bonds is a prerequisite for all life on earth. Understanding the role of proteins in mediating the formation of these bonds is important for understanding biological mechanisms in evolution, as well as for designing {\textquoteleft}{\textquoteleft}green catalysts{\textquoteright}{\textquoteright}. In this work, the ability of silk fibroin (SF) proteins to mediate selective C-C bond formation under mild conditions was comprehensively evaluated and compared between different SF-based materials and other proteins. Aqueous SF solution (ASFS), freeze-dried SF (FDSF), mesoporous SF (MPSF), and SF hydrogel (SFHG) materials were prepared and characterized by a variety of techniques including, among others, FE-SEM, ICP-OES, FT-IR, and TGA. The nitroaldol (Henry) reaction, Knoevenagel condensation, and direct aldol reaction were used as models for this study, in which the recovery and reusability of the protein was also evaluated.

}, keywords = {Aldol-like reactions, C-C Bond formation, Knoevenagel condensation, Proteins, Silk fibroin}, issn = {2168-0485}, doi = {10.1021/sc500184r}, author = {Kuehbeck, Dennis and Ghosh, Munmun and Sen Gupta, Sayam and Diaz, David Diaz} } @article {47412, title = {Nickel-catalyzed C-H bond functionalization of azoles and indoles}, journal = {Chemical Record}, volume = {21}, year = {2021}, month = {DEC}, pages = {3573-3588}, type = {Article}, abstract = {

Direct C-H functionalization of privileged and biologically relevant azoles and indoles represents an important chemical transformation in molecular science. Despite significant progress in the palladium-catalyzed regioselective C-H functionalization of azoles and indoles, the use of abundant and less expensive nickel catalyst is underdeveloped. In the recent past, the nickel-catalyzed regioselective C-H alkylation, arylation, alkenylation and alkynylation of azoles and indoles have been substantially explored, which can be applied to the complex organic molecule synthesis. In this Account, we summarize the developments in nickel-catalyzed regioselective functionalization of azoles and indoles with a considerable focus on the reaction mechanism.

}, keywords = {azoles, C-C Bond formation, C-H functionalization, indoles, Nickel}, issn = {1527-8999}, doi = {10.1002/tcr.202100113, Early Access Date = JUN 2021}, author = {Jagtap, Rahul A. and Punji, Benudhar} } @article {49027, title = {Tridentate NacNac tames T-shaped nickel(I) radical}, journal = {Chemistry- a european journal}, volume = {30}, year = {2024}, month = {FEB}, type = {Article}, abstract = {

The reaction of a nickel(II) chloride complex containing a tridentate beta-diketiminato ligand with a picolyl group [2,6-iPr2-C6H3NC(Me)CHC(Me)NH(CH2py)]Ni(II)Cl (1)] with KSi(SiMe3)3 conveniently afforded a nickel(I) radical with a T-shaped geometry (2). The compound{\textquoteright}s metalloradical nature was confirmed through electron paramagnetic resonance (EPR) studies and its reaction with TEMPO, resulting in the formation of a highly unusual three-membered nickeloxaziridine complex (3). When reacted with disulfide and diselenide, the S-S and Se-Se bonds were cleaved, and a coupled product was formed through carbon atom of the pyridine-imine group. The nickel(I) radical activates dihydrogen at room temperature and atmospheric pressure to give the monomeric nickel hydride. A thermally stable, T-shaped, nickel(I) radical was straightforward obtained by reduction of a tridentate nacnac nickel(II) chloride with KSi(TMS)3. The metalloradical character of the compound was demonstrated by the formation of a highly unusual nickeloxaziridine complex upon addition of TEMPO. The Ni(I) species displays a rich chemistry towards activation S-S, and Se-Se bond leading to unusual C-C coupled product as well as dihydrogen activation at room temperature and atmospheric pressure to generate monomeric nickel hydride.+image

}, keywords = {C-C Bond formation, Hydrogen Activation, Metalloradical, Nickel, Tridentate nacnac}, issn = {0947-6539}, doi = {10.1002/chem.202303957}, author = {Pahar, Sanjukta and Sharma, Vishal and Raj, K. Vipin and Sangole, Mayur P. and George, Christy P. and Singh, Kirandeep and Vanka, Kumar and Gonnade, Rajesh G. and Sen, Sakya S.} }