Ar igid naphthalenediamine framework has been used to prepare antimony hydrides that feature LUMO shapes and energies similar to those found in secondary boranes.B y exploiting this feature,w ei ntroduce the first examples of uncatalyzed hydrostibination reactions of robust CC, C=C, C = O, and N = Nb onds as new elementary hydrometalation reactions analogous to hydroboration. These results endorse the notion of ad iagonal relationship between the lightest p-block element and the heaviest Group 15 elements and may lead to the conception of novel reaction chemistry.

The CÀ N cross-coupling of (hetero)aryl (pseudo)halides with NH substrates employing nickel catalysts and organic amine bases represents an emergent strategy for the sustainable synthesis of (hetero)anilines. However, unlike protocols that rely on photoredox/electrochemical/reductant methods within Ni I/III cycles, the reaction steps that comprise a putative Ni 0/II CÀ N cross-coupling cycle for a thermally promoted catalyst system using organic amine base have not been elucidated. Here we disclose an efficient new nickelcatalyzed protocol for the CÀ N cross-coupling of amides and 2'-(pseudo)halide-substituted acetophenones, for the first time where the (pseudo)halide is chloride or sulfonate, which makes use of the commercial bisphosphine ligand PAd2-DalPhos (L4) in combination with an organic amine base/halide scavenger, leading to 4quinolones. Room-temperature stoichiometric experiments involving isolated Ni 0, I, and II species support a Ni 0/II pathway, where the combined action of DBU/NaTFA allows for room-temperature amide cross-couplings.

We report on our successful development of the first metal-catalyzed mono-α-arylation of carbonyl compounds employing a soluble organic base. The scope of these Ni/DalPhos-catalyzed transformations encompasses a range of (hetero)aryl halides (Cl, Br, I) and phenol-derived electrophiles (sulfonates, carbonates, carbamates, sulfamates), in-cluding active pharmaceutical ingredients (chloroquine, clozapine), in combination with the typically problematic feedstock small molecule substrates acetone, dimethylacetamide, and for the first time with any metal catalyst/ base, ethyl acetate.

The addition of Sb-H bonds to alkynes was reported recently as a new hydroelementation reaction that exclusively yields anti-Markovnikov Z-olefins from terminal acetylenes. We examine four possible mechanisms that are consistent with the observed stereochemical and regiochemical outcomes. A comprehensive analysis of solvent, substituent, isotope, additive, and temperature effects on hydrostibination reaction rates definitively refutes three ionic mechanisms involving closed-shell charged intermediates. Instead the data support a fourth pathway featuring neutral radical Sb II and Sb III intermediates. Density Functional Theory (DFT) calculations are consistent with this model, predicting an activation barrier that is within 1 kcal/mol of the experimental value (Eyring analysis) and a rate limiting step that is congruent with experimental kinetic isotope effect. We therefore conclude that hydrostibination of arylacetylenes is initiated by the generation of stibinyl radicals, which then participate in a cycle featuring Sb II and Sb III intermediates to yield the observed Z-olefins as products. This mechanistic understanding will enable rational evolution of hydrostibination as a methodology for accessing challenging products such as E-olefins.

Substrate-product analogues, designed based on partial movement of the sec-butyl side chain during catalysis, inhibit isoleucine 2-epimerase.