3- Acetyl-l-methoxyindole

These types of compounds are expected to be produced by utilizing nucleophile substitution reaction at the 2 position of l-methoxyindole-3-carbaldehyde (115a) and 3-acetyl-1-methoxyindole (107). In practice, after conversion of 115a to 195a (53%) as described in Section IV.J, 195a is allowed to react with various amines. Consequently, many derivatives of 271 are obtained. Typical examples (271a-c) are shown in the scheme (99H1157). 

Merour, J.Y., Coadou, J.Y., and Tatibouet, E, Syntheses of 2(5)-substituted l-acetyl-3-oxo-2,3-dihy-droindoles, 3-acetoxy-l-acetylindoles, and of 2-methyl-5-methoxyindole-3-acetic acid. Synthesis, 1053, 1982. 

The synthesis of 7-methoxyindole was accomplished starting from 1-acetylindoline (34). Regioselec-tive intr uction of iodine was achieved using thallium trifluoroacetate, then potassium iodide. Deacetylation and oxidation to the indole (35), followed by reaction with sodium methoxide in DMF, gave the 7-methoxyindole (36) in 48% overall yield (Scheme 13). More recently, Somei et al have reported that treating the intermediate thallium species with copper(II) sulfate pentahydrate gives directly the l-acetyl-2,3-dihydro-7-hydroxyindole (37) in 42% yield (Scheme 14). It remains to be seen whether this is a general process. 

Dehydrogenation of indoUnes using DDQ has been used to prepare 6-nitroindole (benzene, reflux, 86%) [32], 7-bromo-5-nitroindole (98%) [33], 6-azido-4,5,7-trif-luoroindole (benzene, 88%) [34], 4,5,6,7-tetrahydroindole (benzene, reflux, 68%) [35], methyl l-acetyl-2-cyclopro-pyl-5-methoxyindole-3-carboxylate (toluene, reflux, 87%) [36], 5,6-dicyano-l-methylindole (benzene, reflux, 97%)... 

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