DFT Analysis into the Calcium(II)-Catalyzed Coupling of Alcohols With Vinylboronic Acids: Cooperativity of Two Different Lewis Acids and Counterion Effects

Abstract

The mechanism of the calcium-catalyzed coupling of alcohols with vinylboronic acids has been analyzed by means of DFT computations. This study reveals that the calcium and the boron Lewis acids associate to form a superelectrophile able to promote a pericyclic group

Calcium Bistriflimide-Mediated Sulfur(VI)–Fluoride Exchange (SuFEx): Mechanistic Insights toward Instigating Catalysis

“…Second, like group 3 compounds, Ca 2+ is a strong Lewis acid, especially when coordinated to weakly binding ligands such as fluorides (F – ), triflates (OTf – ), bistriflimides (NTf 2 – ), or 1:1 bistriflimide/hexafluorophosphate (PF 6 – ) counterions. These Ca 2+ salts form Lewis acid/base adducts to activate otherwise weakly electrophilic compounds such as alcohols, − carbonyls, − olefins, − and boronic acids for subsequent coupling with nucleophilic reagents, notably also with relatively high tolerance to air and moisture. In our recent reports, we employed Ca 2+ salts for the first time to activate a different class of compoundssulfur­(VI) fluorides. , …”

Reversible hydrosilane addition to pyridines enabled by low-coordinate Ca(ii) and Yb(ii) hydrides

“…The meta -hybrid M062X functional was successfully used for studies of catalytic reactions involving calcium complexes. 36 The combination of the M062X functional and DGDZVP basis set earlier predicted correctly the thermodynamics and kinetics of reactions of 14 group complexes. 37 The resulting catalytic model (Fig.…”

Calcium-catalysed synthesis of amines through imine hydrosilylation: an experimental and theoretical study

“…It has previously been shown that Ca(NTf 2 ) 2 and PF 6 salts underwent anion metathesis to form KNTf 2 and Ca(NTf 2 )PF 6 . 20 The latter salt, more Lewis acidic than Ca(NTf 2 ) 2 and displaying two binding sites available on the calcium center, was reported to activate a wide range of substrates such as cyclopropanes, [39][40] carbonyl compounds, [41][42] alcohols, [43][44][45][46][47][48] alkenes 49,50 or more recently sulfonyl 51,52 fluorides. 20,28,53 Ca(NTf 2 )PF 6 , whose Lewis acidity has been evaluated by the Childs method, 41 has also been associated with hexafluoroisopropanol as the solvent and the resulting system shown by Gandon and Leboeuf to be highly active in various transformations including Aza-Piancatelli, 54,55 hydroarylation, 56 or hydroamidation 57 or hydroacyloxylation 58 reactions.…”