Direct CC triple bond formation from the CC double bond with potassium tert-butoxide in dimethylformamide containing trace amounts of oxygen

Abstract

A novel and facile method for direct acetylenic bond formation from the C=C double bond by treatment with KOBut in dimethylformamide has been found both in a 9,l O-bis(4'-substituted styry1)anthracene series and in a 4-su bstituted 4'-nitro-stil bene series; its scope and limitations have been examined.The development of methods of formation of the G C triple bond in organic structures has been amply reviewed in recent years.1 The classical method of formation of the acetylenic bond is elimination of a stable substance from a more

Mechanistic Study of an Improbable Reaction: Alkene Dehydrogenation by the Δ12 Acetylenase of Crepis alpina

“…The acetylenase-catalyzed reaction is a truly remarkable transformation which has no precedent in the repertoire of biochemical oxidizing systems such as cytochromes P450. , The process is highly unusual in mechanistic terms since the direct dehydrogenation of alkenes to alkynes is known only to occur when the starting material is activated to attack by strong bases …”

“…8,9 The process is highly unusual in mechanistic terms since the direct dehydrogenation of alkenes to alkynes is known only to occur when the starting material is activated to attack by strong bases. 10 What is perhaps most puzzling is the fact that the acetylenasemediated reaction proceeds when an energetically far more facile reaction pathway, namely, epoxidation, would appear to be available. Interestingly, a FAD2-like enzyme found within the genus Crepis, bearing a high degree of sequence similarity to the C. alpina acetylenase, converts a linoleoyl substrate exclusively to vernolate (12,13-epoxyoleate).…”

MOF-Triggered Synthesis of Subnanometer Ag02 Clusters and Fe3+ Single Atoms: Heterogenization Led to Efficient and Synergetic One-Pot Catalytic Reactions

“…Here, we would like to comment on the relevance of this result. In fact, it is difficult to find in the literature any procedure that directly converts an alkene to an alkyne in the same flask − and, to our knowledge, a catalytic version of this transformation has only previously been reported with Pd supported in polyamine, which we could not reproduce in our hands. Besides, the Fe 3+ Ag 0 2 @MOF catalyst could be reused after filtration, being able to be recycled up to 5 times while retaining moderately good yields (Figure S25).…”

Crystallographic and spectroscopic studies on persistent triarylpropargyl cations

“…Reports on the triarylpropargyl cations are elusive due to the transient nature, stemming from the presence of an electron-withdrawing -C≡C-moiety attached to the cationic centre. While several attempts have been made to elucidate its electronic state, [10][11][12][13][14] there are currently no examples of triarylpropargyl cations that are stable enough for investigation by X-ray crystallography.…”