61693-02-5Relevant academic research and scientific papers
Alkynyl N-Nosylhydrazones: Easy Decomposition to Alknynl Diazomethanes and Application in Allene Synthesis
Yang, Yang,Liu, Zhaohong,Porta, Alessio,Zanoni, Giuseppe,Bi, Xihe
, p. 9009 - 9013 (2017/07/11)
The decomposition of N-tosylhydrazones is a safe and convenient method for the generation of donor carbenes. However, alkynyl carbenes cannot be isolated by this route because they readily undergo intramolecular cyclization to pyrazoles as soon as formed from alkynyl N-tosylhydrazones. Here, the use of alkynyl N-nosylhydrazones for the in situ generation of alkynyl carbenes and their coupling reaction with boronic acids under metal-free conditions is reported, giving rise to a wide array of di- and trisubstituted allenes. Preliminary mechanistic investigations demonstrated that γ-protodeboration of propargyl boric acid was responsible for the initial allene formation. This methodology based on the nosyl group allows for novel transformations that involve an alkynylcarbene transient species.
Catalytic synthesis of allenes via isomerization of alkynes under phase- transfer catalyzed conditions
Oku, Makoto,Arai, Shigeru,Katayama, Kimiko,Shioiri, Takayuki
, p. 493 - 494 (2007/10/03)
Catalytic isomerization of alkynes to allenes under phase-transfer catalyzed conditions is described. Commercially available quaternary ammonium salt such as tetrahexylammonium bromide acts as a very effective promoter to accelerate the reaction under mil
Electron Demand in the Transition State of the Cyclopropylidene to Allene Ring Opening
Warner, Philip,Sutherland, Robert
, p. 6294 - 6300 (2007/10/02)
The electronic structure of the transition state for the cyclopropylidene to allene conversion has been probed.The methodology involved the relative rates of ring opening vs trapping by MeOH for a series of variously substituted 2,3-diarylcyclopropylidenes.With the assumption that the rate of trapping was unaffected by substituents, a Hammett correlation was constructed.The negative value (-0.72) for ρ indicated that the carbenic center attracts electron density in the ring-opening transition state, much like the cyclopropyl cation to allyl cation transition state.Temperature-dependent studies showed that the observed preference for ring opening was driven by entropy factors.Also, using reasonable estimates for the close to diffusion-controlled trapping activation enthalpies, the derived enthalpies for ring opening were in close agreement with the best theoretical values.
