[3+ 2] Cycloadditions and Protonation by Alcohols of Photochemically Generated Nitrile Ylides from 2 H-Azirines. Formation and Reactivities of Azaallenium Cations

E Albrecht, J Mattay, S Steenken

Index: Albrecht, Evelyn; Mattay, Jochen; Steenken, Steen Journal of the American Chemical Society, 1997 , vol. 119, # 48 p. 11605 - 11610

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Citation Number: 27

Abstract

On photolysis of 2 H-phenylazirines in acetonitrile or alcohol solution with 248 nm laser light, phenylnitrile ylides are formed by heterolytic cleavage of the CC bond of the azirines. The absorption spectra of the ylides are characterized by two strong bands, at ca. 240 and 280 nm, and a weak band, at 380 nm. Electron-deficient olefins react with the nitrile ylides by 1, 3- dipolar cycloaddition to yield 5-membered N-heterocycles (rate constants between 4× 105 ...