An unprecedented scandium-catalysed hydroboration of alkynes and alkenes has been achieved with HBpin in presence of catalytic amount of NaBHEt3.

An efficient catalytic system based on a Co­(II)-NHC precursor has been developed for the cross coupling of bis(pinacolato)­diboron with aryl halides including aryl chlorides, affording the aryl boronates in good to excellent yields. A wide range of functional groups are tolerated under mild reaction conditions. The reaction shows excellent chemoselectivity for bromide over chloride. Preliminary mechanistic investigations show that the catalytic cycle may rely on a cobalt­(I)–(III) redox couple.

Metal-ligand coordination involving hydrogen-bond-functionalized ligands was employed rationally to get an easy access to a series of metallogelators derived from 3-pyridyl derivatives of nonsteroidal anti-inflammatory drugs [e.g., ibuprofen, sulindac, and flurbiprofen designated as 3-pyIBU, 3-pySUL, and 3-pyFLR, respectively] and biogenic metal centers [Zn(II), Cu(II), Mn(II), and Ag(I)]. A total of 13 metallogels (MG1-MG13) were obtained by allowing the ligands and the metal salts to react in dimethyl sulfoxide (DMSO)/water at room temperature. A slightly different solvent system (DMSO/water/MeOH) afforded four crystalline coordination complexes of 3-pyIBU, namely, [{Cu(3-pyIBU)(DMSO)}(NO)] (CC1), [{Ag(3-pyIBU)}(BF)] (CC2), [{Ag(3-pyIBU)}(ClO)] (CC3), and [{Cu(3-pyIBU)(CHOH)}(OTf)] (CC4), which were fully characterized by single-crystal X-ray diffraction. However, none of these coordination complexes produced metallogels-the results corroborated well with the rationale, based on which the metallogelators were obtained. Two selected metallogels (MG3 and MG9) could be leached out from the corresponding metallogels to the bulk solvent to the extent of 51 and 59%, respectively after 24 h of incubation at 37 °C, indicating their plausible use in topical application. Moreover, one of the selected metallogelators, i.e., MG9, displayed anti-inflammatory response and was able to inhibit the migration of highly aggressive human breast cancer cells MDA-MB-231, suggesting its plausible use as anticancer agent.

Ar egioselective hydroboration of alkynes has been developed by using commerciallya vailable zinc triflate as ac atalyst, in the presenceo fc atalytic amount of NaBHEt 3 .T he reaction tolerates aw ide range of terminal alkynes having several synthetically useful functional groups and proceeds regioselectivelyt of urnish hydroborated products in moderate to excellent yields.T his system shows moderate chemoselectivity towards terminal CCb ond over terminala nd internal C=Cb ond and internal CCb ond. Scheme1.Examples of a) Borylation using borylzinc as at ransfer reagent, b) alkyne hydroboration via borylzincate intermediate,c)hydroborationo f N-heterocycles, d) This work:Zinc-catalysed hydroboration of alkynes.Scheme3.Chemoselectivity experiments (a-b;using standard reaction conditions:alkynes or alkenes (0.2 mmol), Zn(OTf) 2 (5 mol %), NaBHEt 3 (5 mol %), HBpin (1 equiv), toluene (1.0 mL) for 10 ha t8 08C). Yields weredetermined by 1 HNMR, using nitromethaneasa ni nternals tandard.Scheme4.Deuterium labelling experiment:a)Hydroboration of 1a-D with HBpin.b )Hydroboration of 1a with DBpin.Scheme5.Stoichiometric reaction between:a)zinc triflate and sodium triethylborohydride,a nd furtherw ith 1a,b)B and HBpin.