Electronic influence in the oxidative addition step toward the regioselectivity of Larock Heteroannulation

Name: Kanyapat Yiamsawat

LCSH: Kasetsart University -- Theses. M.S. (Chemistry) 2021

Classification :.LCCS: QD401

LCSH: Kasetsart University. -- Department of Chemistry -- Theses

LCSH: Indole

LCSH: Aromatic compounds

LCSH: Palladium catalysts

Abstract: Larock heteroannulation is a convenient and effective method to construct 2,3˗diarylindoles from 2˗iodoaniline and diarylacetylene. Two regioisomeric products are obtained when an unsymmetrical alkyne is used. The regioselectivity of the reaction is governed by both the steric and electronic properties of the alkyne reactant. In this work, the electronic effect from the substituents on the 2-iodoaniline reactants toward the regioselectivity was investigated. Initially, six diarylacetylenes were prepared via Sonogashira coupling reaction providing the desired products in 90-99% yields. Subsequently, the 2-iodoaniline derivatives bearing electron-donating and electron-withdrawing groups at the para position to the iodo group were synthesized via iodination as the key step, yielding the trisubstituted benzenes in 26-64% yields. Subsequently, the trisubstituted benzenes and a series of diarylacetylenes were subjected to Larock heteroannulation reaction, and the regioselectivity of the indole products in each case was assessed. The regioselectivity of the reaction was primarily influenced by the electronic properties of the diarylacetylene, indicating the carbopalladation step as the key player on the regioselectivity. Although the electronic properties of the 2-iodoanilines did not show a strong influence on the regioselectivity, the reaction rate was significantly affected. The reactions of the electron-deficient iodoaniline proceeded smoothly with high conversion, while the reactions of the electron-rich iodoaniline were incomplete. The results reported herein lay a foundation for understanding the relationship between the two catalytic steps, oxidative addition, and carbopalladation, in the Larock heteroannulation reaction.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Pitak Chuawong

Role: Thesis Advisor

Name: Pimpa Hormnirun

Role: Thesis CO-Advisor

Name: Pakorn Wattana-Amorn

Role: Thesis CO-Advisor

Created: 2021

Modified: 2025-07-19

Issued: 2025-07-19

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2564/kanyapat-yia-all.pdf

CallNumber: QD401 .K36

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Chemistry

Grantor: Kasetsart University

©copyrights Kasetsart University

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