Calcium‐Catalyzed Hydroarylation of Alkenes at Room Temperature

Scope and advances in the catalytic propargylic substitution reaction

“…Recently, calcium-based Lewis acid catalyst has been used by the group of Niggemann for the nucleophilic substitution of benzylic and allylic alcohols under very mild reaction conditions. 56,57 In further pursuit towards the cost-effective methodology for propargylic substitution reaction avoiding costly transition metals, Niggemann and co-workers in the year 2011 developed an efficient calcium-catalyzed allylation of p-activated alcohols 23 with diverse silyl-based carbanions 63 under very mild reaction conditions, Scheme 25. 58 The reaction of propargylic alcohols 23 and allyltrimethylsilane 63 in presence of 5 mol% each of Ca(NTf 2 ) 2 and Bu 4 NPF 6 proceeded smoothly at room temperature in dichloromethane to give the desired allylated product 64 aer 1 h as a 2.7 : 1 mixture of allylated regioisomers in good yield.…”

Calcium‐Catalyzed Direct Coupling of Alcohols with Organosilanes

“…We recently reported a novel calcium-based, highly Lewis acidic catalyst system for the dehydration of benzylic, allylic, and propargylic alcohols and their subsequent reaction with nucleophilic arenes under very mild reaction conditions. [2,3] We have now turned our attention towards catalytic C-C bond formation with water-tolerant organometallic reagents. The general utility of unsaturated organosilicon compounds as carbanion surrogates is well recognized.…”

Calcium(II)‐Catalyzed Intermolecular Hydroarylation of Deactivated Styrenes in Hexafluoroisopropanol

“…[12] Herein, we demonstrate that the combination Ca 2+ /HFIP can be apowerful tool to promote hydroarylation reactions featuring highly deactivated styrenes as electrophiles (Scheme 1d). [13] Thereaction proved to be general and compatible with awide range of styrenes and aromatic nucleophiles.D FT computations and deuterium labeling experiments were also performed to address the mechanism of this new reaction. Scheme 1.…”