Indole-3-carbaldehyde thallation

Thallation of l-methoxyindole-3-carbaldehyde with thallium trisfluo-roacetate followed by treatment with potassium iodide gave the 4-iodo derivative in 91% yield, and this has been converted into many other 1-methoxyindole derivatives (86CPB677). When the thallated indole reacted with methyl acrylate in the presence of a catalytic quantity of pal-ladium(ll) acetate, 47% of the product was the 4-derivative 160, but 11% of the 5-isomer was also formed (86CPB4116). 

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