tative yield. These results suggest that the Si - O bond of 1-hydroxyindole is remarkably weaker than we expected. However, the TBDMS group is shown to be useable for the protection of the 1-hydroxy moiety.

When 54 is treated with hydrogen halides, rapid nucleophilic substitution reactions take place within 10 min at room temperature (Table 7). In the reaction with HCl/t-BuOH, 5-chloro- (131, 60%), 7-chlorotryptamines (132, 4%), and tryptamine (55, 3%) are produced. The reaction of 54 with HBr/t-BuOH affords 5-bromo- (36), 7-bromotryptamines (59), and tryptamine (55) (entry 1). In the same reaction, the employment of formamide as a solvent dramatically changes the reaction pathway to yield 1-hydroxytryptamine (52) as a sole product (entry 2) [24].

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