2026-10-14T17:54:04Z https://api.figshare.com/v2/oai

oai:figshare.com:article/33942647 2026-09-19T14:14:18Z category_1 category_4 category_14 category_21 category_272 category_873 category_734 category_135 portal_63 item_type_3 month_year_09_2026

Unveiling the Critical Roles of Amine Additives and Water for Half-Sandwich Sc Catalysts in Annulation Reactions Yongfang Zhang (2643442) Yi Gao (112914) Zihan Zhang (3117441) Rongyu Li (14307097) Xueqing Song (9275126) Longfei Li (589618) Biophysics Biochemistry Molecular Biology Biotechnology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Biological Sciences not elsewhere classified Computational Biology withdrawing substituents inhibit study theoretically investigates computed results suggested >, thereby establishing 6 kcal mol 4 kcal mol 31 kcal mol earth metal catalysts unique catalytic properties mediated hydrogen exchange inert sc – sandwich scandium catalyst gibbs free energy sandwich sc catalysts >- selective pathway newly identified 1 annulation reactions rare >- butyl α nmc </ b </ b ></ 5 </ sub 4 </ sub ligand framework facilitate 3 </ sub sc catalysts sc catalyst trans </ tert </ cis </ >- diastereoselective annulation pathway energy span catalyst structures unsaturated aldimines unique c systematically elucidated substituent effects promoted borrowing methyl cinnamaldimine kinetic penalty hydrogen ring critical roles cp ligand amine additives alkenes catalyzed Rare-earth metal catalysts have unique catalytic properties. In order to uncover the critical roles of amine additives and water for Sc catalysts, this study theoretically investigates the <i>trans</i>-diastereoselective [3 + 2] annulation of α,β-unsaturated aldimines with alkenes catalyzed by a C₅Me₄SiMe₃-ligated half-sandwich scandium catalyst. 1-adamantylamine (AdNH₂) is found to facilitate the cyclization step by lowering the Gibbs free energy by 3.6 kcal mol^–1 and promote catalyst regeneration via 1-adamantylamine-mediated hydrogen exchange. The newly identified 1-adamantylamine-promoted borrowing-hydrogen ring-opening/ring-closing steps enable configuration inversion of intermediate <b>5</b><i><b>t</b></i> to its isomer <b>5</b><i><b>c</b></i>, thereby establishing a <i>cis</i>-selective pathway with an energy span of 29.4 kcal mol^–1. The important water-assisted [3 + 2] annulation pathway is unveiled with an energy span of 31 kcal mol^–1, and the inert Sc–O bonds of Sc–OH intermediates could impose a kinetic penalty that attenuates overall catalytic efficiency. The substituent effects of the unique C₅Me₄SiMe₃ ligand on the Sc catalyst are systematically elucidated by modulating the catalyst structures. The computed results suggested that electron-withdrawing substituents inhibit the rate-determining styrene insertion step, while the van der Waals interactions between the Cp ligand and the <b>NMC</b> (<i>N-tert</i>-butyl α-methyl cinnamaldimine) ligand framework facilitate this step. 2026-09-19T00:00:00Z Dataset Dataset 10.1021/acs.joc.6c01623.s001 https://figshare.com/articles/dataset/Unveiling_the_Critical_Roles_of_Amine_Additives_and_Water_for_Half-Sandwich_Sc_Catalysts_in_Annulation_Reactions/33942647 CC BY-NC 4.0