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Photochemisches Verhalten von N‐Acyl‐11‐methyl‐hexahydrocarbazolen

1973; Wiley; Volume: 56; Issue: 7 Linguagem: Inglês

10.1002/hlca.19730560746

1522-2675

Barbara Winkler‐Lardelli, Hans Jürǵen Rosenkranz, Hans‐Jürǵen Hansen, H. Schmid, B. Blank, Hanns Fischer,

Synthesis and Biological Evaluation

Abstract The irradiation of N‐acylated 11‐methyl‐1,2,3,4,10,11‐hexahydrocarbazoles (compounds 6–10 ) and of the 8‐methoxy derivatives 11–13 in hexane solution, with 254 nm light, in the presence of air, leads to 11‐methyl‐2,3,4,11‐tetrahydro‐1 H ‐carbazole ( 2 ) (table 1) and its 8‐methoxy derivative 21 , respectively (scheme 2). Furthermore the 8‐acylated products. 14, 15, 16, 18 , are formed in minor amounts by a “photoanilide” rearrangement. Irradiation of the N‐acetyl‐8‐methoxy‐indoline 12 gives in addition (by elimination of the 8‐methoxy group) the 8‐acetyl‐indoline 14 and, by coupling, the dimeric compound 23 (schemes 2 and 4). Irradiation of the N‐formyl‐indoline 6 yields, besides the indolenine 2 the indoline 1 (table 1). The mechanism of the anaerobic part of these photoreactions were investigated by CIDNP experiments. It is possible to convert directly indoline 1 to the indolenine 2 , in 33% yield, by irradiation at 60° in the presence of oxygen.