Calcium‐Catalyzed Cyclopropanation

Electron Flow in Reaction Mechanisms—Revealed from First Principles

“…Figure S3 in the Supporting Information reveals that neither canonical nor large-basis Pipek-Mezey orbitals can describe this mechanism, while Boys orbitals exaggerate its complexity. ).A ne xcellent example was recently reported by Haven et al [33] They developed ac alcium-catalyzed cyclopropanation, in which four bonds are formed by ar eaction path with only one transition state and no intermediates in-between. ).A ne xcellent example was recently reported by Haven et al [33] They developed ac alcium-catalyzed cyclopropanation, in which four bonds are formed by ar eaction path with only one transition state and no intermediates in-between.…”

Cooperative Catalysis: Calcium and Camphorsulfonic Acid Catalyzed Cycloisomerization of Diynols

“…[17a] In addition, ac yclopropanation of enynols was shown to proceed via allenyl cations derived from ar earrangemento ft he initially formed propargyl cations. [18] Furthermore, the Ca 2 + -catalyzed cycloisomerization of enynes [19] and the intermolecular addition of alcohols to alkynes [20] yield enols, formed upon the trapping of av inyl cation with water,i na nalogy to previously published work on cationic carbocyclizations of alkynes. [21] Combination of these two pathways opens up an excellent route towards allene-enols C'.I no ther words, the ionization of ad iynol 3 leads to the formation of an allenylc ation 4 that transforms to av inyl cation upon nucleophilic attack of the tethered alkyne followed by its interceptionw ith water (Scheme 2).…”

Elektronenfluss in Reaktionsmechanismen – enthüllt aus quantenmechanischen Grundprinzipien

“…[34] ). Ein exzellentes Beispiel einer solchen Reaktion wurde kürzlich von Haven et al [33] [12,35] deuten ihr Potenzial zur Aufdeckung komplexer Mechanismen an. Der hier gefundene Zusammenhang mit der Quantenchemie ebnet den Wegz ur Untersuchung von intuitiven Reaktionsmechanismen in einer nie dagewesenen Direktheit und Detailfülle.Ein IBO-Programm ist frei verfügbar.…”

“…Die Cyclopropanierung von Haven et al Vier Bindungen werden entlang eines einzigen abfallenden Reaktionspfades gebildet. [33] Durch Verfolgung der IBOs kçnnen wir den präzisen Reaktionsmechanismus ableiten (Mitte). Gruppierte Bilder zeigen IBOs am selben IRC-Punkt;g etrennte Bilder werden genutzt, um Überlappungen der IBOs zu vermeiden.…”