Mechanism of the Fe(iii)-catalyzed synthesis of hexahydropyrimidine with α-phenylstyrene: a DFT study

Yaxuan Cheng; Siwei Yang; Chaoyu Zhao; Huiling Liu

doi:10.1039/d2ra02727e

Mechanism of the Fe(iii)-catalyzed synthesis of hexahydropyrimidine with α-phenylstyrene: a DFT study

RSC Adv. 2022 Jul 15;12(32):20523-20529. doi: 10.1039/d2ra02727e. eCollection 2022 Jul 14.

Authors

Yaxuan Cheng¹, Siwei Yang¹, Chaoyu Zhao¹, Huiling Liu¹

Affiliation

¹ Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, College of Chemistry, Jilin University Liutiao Road 2 Changchun 130023 China huiling@jlu.edu.cn.

Abstract

It is very important to develop multiple C-H substitution reactions of simple alkenes to obtain complex unsaturated components. The present study focuses on a theoretical investigation of the plausible mechanism in the Fe(OTf)₃-catalyzed tandem amidomethylative reactions of α-phenylstyrene. Bis(tosylamido)methane is activated by Fe(OTf)₃ to form tosylformaldimine and its Fe(OTf)₃-adduct. The Fe(OTf)₃-adduct undergoes an intermolecular aza-Prins reaction with α-phenylstyrene to form allylamide. The DFT data support the formation of the hexahydropyrimidine derivative from allylamide, and "condensation/iminium homologation/intramolecular aza-Prins" is the optimal reaction path. At the same time, a possible reaction pathway for the conversion of the hydrolysate 1,3-diamide derivative to the hexahydropyrimidine (HHP) derivative is given. This work is thus instructive for understanding Fe(iii)-based tandem catalysis for the amidomethylative multiple-substitution reactions of alkenes.