The Reaction Of3-Alkyl-1-Benzylbenzotriazolium Ylide With α,β-unsaturated Aldehydes, Ketones Or Nitriles

In the presence of a suitable base, the3-alkyl-1-benzylbenzotriazolium ylide was easily formed by the deprotonation of3-alkyl-1-benzylbenzotriazolium halide. However the reactive properties of this specific semi-stability nitrogen ylide are still unexplored till today. In this paper, the reactions of3-alkyl-1-benzylbenzotriazolium ylide with a, β-unsaturated aldehydes, ketones or nitriles were introduced respectively.Part one, the reactions of3-alkyl-1-benzylbenzotriazolium ylide with a, β-unsaturated aldehydes were reported. Firstly, the3-aikyl-1-benzylbenzotriazolium ylide was formed from the reaction of3-alkyl-l-benzylbenzotriazolium bromide with t-BuOK in a mixed solvent (THF/DMSO=5/1, v/v), then it react with α, β-unsaturated aldehydes to give trans-pyrazolines derivatives with high stereo selectivity. The structures and configurations of these compounds were determined by1H NMR,13C NMR, IR and HRMS. The possible mechanism of this reaction was also proposed.Part two, the reactions between3-alkyl-1-benzylbenzotriazolium ylide and a, β-unsaturated ketones were introduced. In a mixed solvent (THF/DMSO=5/1, v/v), a good yield of trans-pyrazoline derivatives were formed from the reaction of3-alkyl-1-benzylbenzotriazolium ylide with α, β-unsaturated aliphatic ketones. Whereas the high yield of trans-cyclopropanes derivatives were obtained from the reaction of3-alkyl-1-benzylbenzotriazolium yilde with α, β-unsaturated aromatic ketones in DMF. The structures and configurations of these compounds were determined by1H NMR,13C NMR, HRMS and Single-crystal X-ray. The possible mechanism of this reaction and reaction selectivity were also proposed.Part three, the reactions of3-alkyl-l-benzylbenzotriazolium ylide with a,(3-unsaturated nitriles were reported. As expected, high yield of trams-cyclopropane derivatives were obtained from the reaction of3-alkyl-l-benzylbenzotriazolium ylide with2-benzylidenemalononitrile. But it is unexpected that the pyrazole derivatives were obtained from the reaction of3-alkyl-l-benzylbenzotriazolium ylide with cinnamonitrile. The structure and configuration of these compounds were determined by1H NMR,13C NMR and Single-crystal X-ray. The mechanism was also proposed.The last part is the summary of the whole paper. In this part, the selectivity of the reactions between different α,β-unsaturated substrates and3-alkyl-l-benzylbenzotriazolium ylide was explained.