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Linear versus Angular Fischer Indole Annulation: Relative Configuration Determines Regioselectivity
Author(s) -
Diedrich Claas Lüder,
Frey Wolfgang,
Christoffers Jens
Publication year - 2007
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200700351
Subject(s) - chemistry , regioselectivity , annulation , diastereomer , indole test , bicyclic molecule , stereochemistry , aldol reaction , organic chemistry , catalysis
Fischer indole synthesis with bicyclic ketones yields regioselectively linear annulated tetracyclic products when starting from ketones with a relative trans configuration. On the other hand, starting materials with a relative cis configuration give exclusively angular annulated indole derivatives. The starting materials were prepared in optically active form in three steps by a sequence of asymmetric Michael reaction, aldol condensation, and catalytic hydrogenation. The last step yields a mixture of cis and trans diastereoisomers which can be separated by column chromatography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)