Calcium-mediated C(sp3)-H Activation and Alkylation of Alkylpyridines

Main-group metal calcium-mediated alkylpyridine benzylic C(sp³)-H activation and functionalization have been achieved. The reaction of a calcium hydride complex [{(^DIPPnacnac)CaH(thf)}₂] (^DIPPnacnac = CH{(CMe)(2,6-ⁱPr₂-C₆H₃N)}₂) with two equivalents of 2,6-lutidine rapidly yields a monomeric calcium alkyl complex with the release of dihydrogen. A hydride/carbon-bridged binuclear calcium complex [{(^DIPPnacnac)Ca}₂(μ-H){2-Me-6-(μ-CH₂)-Py}(thf)] is obtained from an equimolar treatment of calcium hydride and 2,6-lutidine that is readily converted into mono- or binuclear calcium alkyl complexes upon subsequent addition of 2,6-lutidine. DFT calculations and kinetic studies are conducted to determine their reaction profiles. More significantly, this calcium hydride complex catalyzes regioselective benzylic C-H bond addition of alkylpyridines to a variety of alkenes, affording linear or branched alkylated pyridine derivatives.

Phosphinoborane interception at magnesium by borane-assisted phosphine-borane dehydrogenation

Ph₂PBH₂ is generated and trapped on-metal by addition of B(C₆F₅)₃ to a β-diketiminato magnesium phospidoborane complex, similar reactivity is meanwhile prevented for the analogous calcium-based system by formation of a stable η⁶-toluene complex.

Stoichiometric reactions and catalytic dehydrogenations of amine–boranes with calcium aryloxide

A calcium aryloxide complex reacts with amine–boranes to give unprecedented amine–borane coordinated complexes through Ca⋯H interactions, which serve as active species for catalytic dehydrogenation reactions.

Amido Ca(ii) complexes supported by Schiff base ligands for catalytic cross-dehydrogenative coupling of amines with silanes

Heteroleptic Ca(ii) amides coordinated by multidentate phenolato ligands proved to be efficient catalysts for catalytic cross-dehydrogenative coupling of amines with silanes.

The significance of secondary interactions during alkaline earth-promoted dehydrogenation of dialkylamine-boranes

Reactions of anilidoimine magnesium n-butyl and calcium bis(trimethylsilyl)amide derivatives with Me₂NH·BH₃ at 25 °C resulted in the isolation of complexes containing [NMe₂BH₂NMe₂BH₃]⁻ and [NMe₂BH₃]⁻ anions respectively.

s-Block amidoboranes: syntheses, structures, reactivity and applications

The highly versatile amidoborane compounds of the group 1 and 2 metals are reviewed, with an emphasis on their synthesis, structures and reactivity.

Alkaline-Earth-Catalyzed Dehydrocoupling of Amines and Boranes

Dehydrocoupling reactions between the boranes HBpin and 9-borabicyclo[3.3.1]nonane and a range of amines and anilines ensue under very mild reaction conditions in the presence of a simple β-diketiminato magnesium n-butyl precatalyst. The facility of the reactions is suggested to be a function of the Lewis acidity of the borane substrate, and is dictated by resultant pre-equilibria between, and the relative stability of, magnesium hydride and borohydride intermediates during the course of the catalysis.

Two alternative approaches to access mixed hydride-amido zinc complexes: synthetic, structural and solution implications

In the presence of a bulky N-heterocyclic carbene, Zn(HMDS)₂can be converted in to either a mononuclear amido/hydride complex or a tetranuclear hydride rich cluster depending on the hydride source and reaction conditions employed.