Reaction of 1-f-ButyldimethylsMyloxytryptamine

Generally speaking, a Si - O bond (370 KJ/mol) is stronger than a N - O bond (163 KJ/mol). We can therefore expect that 1-i-butyldimethylsilyloxy-tryptamine (54) would function as a good substrate for the preparation of 5-substituted tryptamines (130) with a concomitant liberation of i-butyldi-methylsilanol from N(1) upon reaction with nucleophiles.

Contrary to expectation, both nucleophiles, NaCN and NaN3, provide only 1-hydroxytryptamine (52) as shown in Table 6 (entries 1 and 2) [24]. In MeOH/H2O (2: 1) Nal affords 52 as well (entry 3), while in MeOH/H2O (1: 10) formation of 52 is not observed at all (entry 4) instead the starting material is recovered. In every case, a product with a nucleophile in the indole nucleus is not detected. The reaction of 54 with TBAF provides 52 in quanti-

Table6 Reaction of 1-i-butyldimethylsilyloxytryptamine with nucleophiles


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