Alternatively, 5-methoxyindole (III) was N-silylated employing tert-butyldimethylsilyl chloride and n-BuLi, and the resulting silyl derivative (V) was brominated with N-bromosuccinimide at -78 C to afford the 3-bromoindole (VI). After lithium-bromine exchange in (VI) with n-BuLi at -78 C, the 3-lithio compound was condensed with N-methyl-D-proline methyl ester (VII) to give the indolyl ketone (VIII). The ketone function of (VIII) was finally reduced employing LiAlH4 in boiling THF.

Silylation of 4-benzyloxyindole (I) employing tert-butyldimethylsilyl chloride and NaH gave the N-silyl derivative (II), which was brominated with N-bromosuccinimide at -78 C to afford the 3-bromoindole (III). After lithium-bromine exchange with n-BuLi at -78 C, the 3-lithio compound was condensed with N-methyl-D-proline methyl ester (IV) to give the indolyl ketone (V). The ketone function of (V) was finally reduced employing LiAlH4 in boiling dioxan, with concomitant cleavage of the benzyl ether to furnish the title compound.