Regioselectivity of Larock indole synthesis using functionalized alkynes.

Regioselectivity of Larock indole synthesis, a palladium-catalyzed heteroannulation between o-iodoaniline and internal acetylene, was estimated using acetylenes substituted with ester and/or Boc-protected amine at the homopropargylic position and with perbenzyl- and unprotected glucose. Low to moderate regioselectivities were observed in all the cases, indicating these functional groups do not exert good directing effects, in the Larock indole synthesis.