217 research outputs found
Apparent Alkyl Transfer and Phenazine Formation via an Aryne Intermediate
Treatment of chlorotriaryl derivatives 3a and 3d or fluorotriaryl derivatives 3b and 3e with potassium diisopropylamide afforded alkyl-shifted phenazine derivatives 5a/5b, rather than the expected 9-membered triazaorthocyclophane 2a. The phenazine derivatives were isolated in 78â98% yield depending on the halogen and alkyl group present. In the absence of the halogen (chloro or fluoro), the apparent alkyl shift proceeds more slowly and cannot proceed via the intermediacy of the aryne intermediate. Mechanistic possibilities include intramolecular nucleophilic attack on an aryne intermediate leading to a zwitterionic intermediate and alkyl transfer via a 5-endo-tet process, or via a Smiles rearrangement
Coordinatively Unsaturated Ruthenium Complexes As Efficient AlkyneâAzide Cycloaddition Catalysts
Synthesis of Saturated Heterocycles via Metal-Catalyzed Formal Cycloaddition Reactions That Generate a CâN or CâO Bond
Cycloaddition reactions of azides and electron-deficient alkenes in deep eutectic solvents: pyrazolines, aziridines and other surprises
The reaction of organic azides and electronâdeficient alkenes was investigated in a deep eutectic solvent. A series of highly substituted 2âpyrazolines was successfully isolated and their formation rationalised by DFT calculations. The critical effect of substitution was also explored; even relatively small changes in the cycloaddition partners led to completely different reaction outcomes and triazolines, triazoles or enaminones can be formed as major products depending on the alkene employed
Cycloaddition Reactions of Azides and ElectronâDeficient Alkenes in Deep Eutectic Solvents: Pyrazolines, Aziridines and Other Surprises
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