A New Synthesis of Difluorodiazirine and the Absolute Reactivity of Difluorocarbene

Abstract

Difluorodiazirine was generated by the reaction of 2,4-dinitrophenoxyfluorodiazirine with lithium fluoride and 15-crown-5 in HMPA. Laser flash photolysis of difluorodiazirine afforded difluorocarbene (CF(2)). Absolute rate constants and activation parameters were determined for the additions of CF(2) to several alkenes.

Distortion/interaction analysis of the reactivities and selectivities of halo– and methoxy–substituted carbenes with alkenes

“…8 Carbene cycloadditions have been extensively studied experimentally and computationally by the groups of Moss and Krogh-Jespersen over the last decade. [9][10][11][12] They combined laser flash photolysis and density functional theory calculations to determine activation parameters for a series of carbene cycloadditions. 13 They found that trends in ∆E ‡ parallel expectations based on considerations of carbene stability and nucleophilicity.…”

Das schwer fassbare Diazirinon, N2CO

“…[6] Über die Synthese von 1 durch Reaktionen von p-Nitrophenoxychlordiazirin mit Halogenidsalzen wurde kürzlich in der Literatur berichtet. [7][8][9][10] In einer nachfolgenden Arbeit [11] wurde allerdings festgestellt, dass die IR-Bande in der früheren Studie [7] nicht dem cyclischen N 2 CO, sondern nur CO in kondensierter Phase zugeordnet werden kann. Somit blieb Diazirinon bis jetzt eine noch nicht entdeckte Spezies.…”

A Half‐Century Odyssey in the Realm of Reactive Intermediates

“…Most excitingly, we also obtained diazirine precursors for dimethoxycarbene, which is the archetypal nucleophilic carbene; [34] dichlorocarbene, which is the iconic carbene of Hine and Doering, [35] and difluorocarbene, which is a storied electrophilic carbene. [36] Each carbene was generated by laser flash photolysis from the corresponding diazirine, enabling spectroscopic characterization and the first measurements of absolute kinetics and activation parameters for the addition reactions of the carbenes to alkenes. An unexpected outcome was evidence for compensation between activation enthalpies and entropies; both parameters increased or decreased in tandem as the alkene substrate was varied.…”