Triflic Acid-Catalyzed
Synthesis of Indole-Substituted
Indane Derivatives via In Situ Formed Acetal-Facilitated
Nucleophilic Addition and 4π-Electron-5-Carbon Electrocyclization
Sequence
Version 2 2021-11-16, 16:17Version 2 2021-11-16, 16:17
Version 1 2021-11-11, 22:03Version 1 2021-11-11, 22:03
journal contribution
posted on 2021-11-16, 16:17authored byGolla Ramesh, Rengarajan Balamurugan
An efficient protocol for the synthesis
of indole-substituted indanes
from o-alkenylbenzaldehydes under acetalization conditions
has been presented. The cyclization occurs via a nucleophilic addition
of indole on the oxacarbenium ion generated from acetal formed under
the reaction condition followed by a conrotatory 4π-electrocyclization
reaction, which takes care of the exclusive diastereoselectivity observed
during the cyclization step. Olefin geometry of o-alkenylbenzaldehyde and the amount of indole play a decisive role
in the success of this cyclization process.