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Synthesis of 2,6‐Dioxo‐1,2,3,4,5,6‐hexahydroindoles by Acid‐ Catalyzed Cyclization of Acetal‐Protected (2,4‐Dioxocyclohex‐1‐yl)acetamides and their Transformation into 5,8,9,10‐Tetrahydro‐6 H ‐indolo[2,1‐ a ]isoquinolin‐9‐ones
Author(s) -
Juma Benard,
Adeel Muhammad,
Villinger Alexander,
Reinke Helmut,
Spannenberg Anke,
Fischer Christine,
Langer Peter
Publication year - 2009
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200800691
Subject(s) - chemistry , acetal , moiety , triflic acid , catalysis , acetic acid , alkene , cyclohexane , medicinal chemistry , organic chemistry
Acetal‐protected (2,4‐dioxocyclohex‐1‐yl)acetic acids were prepared by allylation of dilithiated 1,3‐cyclohexane‐1,3‐diones, protection of the carbonyl groups and oxidation of the alkene moiety. Their reaction with amines afforded the corresponding amides which were transformed, by acid‐catalyzed cyclization, into various 2,6‐dioxo‐1,2,3,4,5,6‐hexahydroindoles. The reaction of the latter with triflic acid resulted in the formation of novel 5,8,9,10‐tetrahydro‐6 H ‐indolo[2,1‐ a ]isoquinolin‐9‐ones.