Acylated indole synthesis, aluminum chloride

NEN1TZESCIJ INDOLE SYNTHESIS. Hydrogenanve acylation of cycloolefins with acid chlorides in the presence of aluminum chloride with five- and six-membered rings, no change in ring size occurs, but with seven-membered rings, rearrangement takes place with formation of a cyclohexane derivative. 

Intramolecular acylations of the Bischler-Napieralski type have been used as crucial steps in the synthesis of indole alkaloids of the yohimbine class <94JCS(Pl)299, 94TL1071>. Also, the aluminum chloride-catalysed reaction of the indolosuccinic anhydride (46) gave the bridged cyclic product (47) rather than the cyclopentanone (49), presiunably because the reaction involves initial acylation at C-3 and reaction via the less strained intermediate is favored. Formation of the cyclopentanone (49) can be achieved using the polyphosphate ester cyclodehydration of the modified intermediate (48) (Scheme 13) <90JCS(Pi)2487>. 

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