Transition metal-catalyzed cross-coupling Heck reactions: A mechanistic study based on Density Functional Theory

Author(s)

Vitor Hugo Menezes da Silva

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2017-08-25

Examining board members

Ataualpa Albert Carmo Braga; Thiago Carita Correra; Nelson Henrique Morgon; Antonio Gustavo Sampaio de Oliveira Filho; Mauro Carlos Costa Ribeiro

• Advisor: Ataualpa Albert Carmo Braga

Abstract

In this work, several examples of Heck reactions were investigated using mostly Density Functional Theory (DFT) methods. At the first part, a new Heck catalytic cycle was proposed with combined anionic and neutral steps initiated by a newly N-heterocyclic carbene (NHC) based palladium (Pd) complex. Posteriorly, the influence of steric demanding of NHC ligand was investigated on selectivity of Heck reaction initially studied. In the case of small NHC ligand, the electronic component is more important than the noncovalent contributions. However, when the crowded NHC ligands were studied only selected density functionals (TPSS-D3, ωB97x-D, BP86-D3, e M06-L), and the wavefunction based method DLPNO-MP2, were capable to predict the experimental selectivity trends reported. Finally, the metal nature was analyzed by a comparison of the nickel (Ni) and Pd catalyzed Heck reactions. The theoretical results provided mechanistic insights that help to understand the low catalytic activity usually reported when Ni catalysts were used and the experimental requirement of cationic intermediates to achieve some efficiency for NHC-Ni-catalyzed Heck coupling. At second part, two representative examples from literature about the enantioselective Heck-Matsuda reactions were theoretically investigated. DFT calculations shown the crucial influence of substrate (olefin) on the selectivity of these reactions. One of cases studied, the selectivity of reaction was improved by the DFT results (AU)

• FAPESP's process: 13/04813-6 - Mechanistic studies of Heck-Matsuda reactions: a theoretical investigation
• Grantee: Vitor Hugo Menezes da Silva
• Support Opportunities: Scholarships in Brazil - Doctorate