Dedication to Professor Valekh M. Ismailov from Baku State University on the occasion
of his 80th anniversary
Abstract
In this review, a fragmentary analysis of 4,5,6,7-tetrahydroindoles was performed
and, on its basis, the existing methods of their synthesis published over the past
15 years have been summarized, and analyzed, as well as, if necessary, an analysis
of earlier works is carried out. The proposed reaction mechanism is considered, as
well as factors that significantly influence the course of the process. Among such
factors: temperature, type and content of the catalyst, promoting additives, method
of the process, etc. Particular attention is paid to fundamentally new methods that
make it possible to synthesize various derivatives of the mentioned heterocyclic systems
from available and cheap reagents, and in some cases under environmentally benign
conditions.
1 Introduction
2 Intramolecular Reactions Leading To Tetrahydroindoles
2.1 Ring Closure Reactions with N–C2 Bond Formation (a)
2.2 Ring Closure Reactions with C2–C3 Bond Formation (b)
2.3 Ring Closure Reactions with C3–C3a Bond Formation (c)
2.4 Ring Closure Reactions with C7a–N Bond Formation (e)
2.5 Ring Closure Reactions with C4–C5 Bond Formation (g)
2.6 Ring Closure Reactions with C3a–C4 Bond Formation (h)
3 Intermolecular Reactions Leading To Tetrahydroindoles
3.1 Ring Closure Reactions with N–C2 + C3–C3a Bond Formation (ac)
3.2 Ring Closure reactions with N–C2 + C7a–N Bond Formation (ae)
3.3 Ring Closure reactions with C3–C3a + C7a–N Bond formation (ce)
3.4 Ring Closure Reactions with N–C2, C3–C3a, and C7a–N Bond Formation (ace)
4 Recovery Processes (Hydrogenation) of Indoles and Oxidation of Perhydroindoles
in the Synthesis of 4,5,6,7-Tetrahydroindoles
5 Conclusion
Key words
tetrahydroindoles - indoles - pyrroles - natural products - fragmentary analysis -
metal catalysis - ring closure reactions
