Photochemische Cycloadditionen von 3‐Phenyl‐2H‐azirinen mit Triphenyl‐vinylphosphoniumbromid. 36. Mitteilung über Photoreaktionen

On irradiation in acetonitrile 3‐phenyl‐2H‐azirines of type 1 react with triphenyl vinyl phosphonium bromide to form in approximative 50% yield 2H‐indoles of type 4 (Scheme 1). In analogy to other photochemical reactions with 2H‐azirines [2] [3] it is assumed that the photochemically generated dipoles 2 react with the triphenyl vinyl phosphonium salt (Scheme 1). The conversion of 1 to 4 represents a new synthesis for 2H‐pyrroles.