01579nas a2200205   4500008004100000022001400041245010000055210006900155260000800224490000700232520086900239653001101108653002901119653001701148653002401165653001601189100002001205700002001225856012801245       2025                        eng d  a1861-472800aCoBr2-catalyzed straightforward synthesis of quinoxalines via dehydrogenative coupling strategy0 aCoBr2catalyzed straightforward synthesis of quinoxalines via deh  cDEC0 v203 a<p>
	Establishing a benign and straightforward protocol for synthesizing biorelevant and synthetically valuable quinoxaline is very important. Herein, we report a simple and efficient protocol for the sustainable synthesis of diverse quinoxaline derivatives catalyzed by cobalt salt. The reaction proceeds through the dehydrogenative coupling of alkyl and aryl ethane 1,2-diols with aryl diamines in the presence of a catalytic CoBr2/K2CO3. The usage of the greener solvent 2-MeTHF and the release of H2 and H2O as the sole byproducts make the process advantageous. The protocol led to the synthesis of diverse quinoxalines bearing synthetically useful functionalities, such as fluoro, chloro, bromo, cyano, trifluoromethyl, and ether. The reaction is presumed to proceed via the dehydrogenative-condensation pathway involving a cobalt-hydride intermediate.</p>
10acobalt10adehydrogenative coupling10aheterocycles10aligand-free process10aQuinoxaline1 aDubey, Shivansh1 aPunji, Benudhar  uhttps://library.ncl.res.in/content/cobr2-catalyzed-straightforward-synthesis-quinoxalines-dehydrogenative-coupling-strategy02238nas 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<p>
	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.</p>
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