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The synthesis of 3,4,4a,9a‐tetrahydro‐2(1 H )‐carbazolones
Author(s) -
Wittekind Raymond R.,
Lazarus Sam
Publication year - 1970
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570070603
Subject(s) - chemistry , trifluoroacetic acid , boron trifluoride , ring (chemistry) , dimer , indole test , medicinal chemistry , trifluoroacetic anhydride , stereochemistry , organic chemistry , catalysis
Cyclization of 4‐(1‐methylindol‐3‐yl)‐2‐butanone and the corresponding 1‐benzyl analog in trifluoroacetic acid furnishes 9‐methyl‐ and 9‐benzyl‐3,4,4a,9a‐tetrahydro‐2(1 H )‐carbazolone, respectively. Under the same conditions, 4‐(indol‐3‐yl)‐2‐butanone gives the dimer, 3‐(3‐oxo‐butyl)‐2‐[3‐(3‐oxobutyl)‐2‐indolinyl] indole. When boron trifluoride etherate is used instead of trifluoroacetic acid, the desired 3,4,4a,9a‐tetrahydro‐2(1 H )‐carbazolone is obtained. The determination of the structure of the tetrahydrocarbazolones is described and the stereochemistry of the ring fusion is discussed.