A robotic AI-Chemist system for multi-modal AI-ready database.

By fusing literature data mining, high-performance simulations, and high-accuracy experiments, robotic AI-Chemist can achieve automated high-throughput production, classification, cleaning, association and fusion of data, and thus develop a multi-modal AI-ready database.

The mechanism and origin of selectivities for NHC-catalyzed synthesis of axially chiral benzothiophene/benzofuran-fused biaryls.

By performing density functional theory (DFT) calculations, we investigated and identified the fundamental pathway for N-heterocyclic carbene (NHC)-catalyzed synthesis of axially chiral benzothiophene-fused biaryls using enal and 2-benzyl-benzothiophene-3-carbaldehyde, which includes (1) nucleophilic attack on enal by the organocatalyst NHC, (2) [1,2]-proton transfer, (3) oxidation, (4) stereoselective formation of the C-C σ bond, (5) intramolecular [2 + 2] cycloaddition, (6) dissociation of NHC, (7) release of CO2, and (8) transformation to axial chirality. Moreover, the calculated results can reasonably explain the observed chemo- and stereoselectivities for the formation of both benzothiophene/benzofuran-fused biaryls in these kinds of reactions. Further non-covalent interaction (NCI) and atoms-in-molecules (AIM) analyses demonstrate that the hydrogen bond interactions are responsible for the stability of key stereoselective transition states. This work would be useful for understanding the origin of stereoselectivity of NHC-catalyzed intermolecular cyclization reactions for the synthesis of axially benzothiophene/benzofuran-fused biaryl compounds.

Electrostatic effects in N-heterocyclic carbene catalysis: revealing the nature of catalysed decarboxylation.

Quantum chemistry is used to investigate the nature of protonated N-heterocyclic carbene (NHC·H+) catalysed decarboxylation recently reported by Zhang et al. (ACS Catal., 2021, 11, 3443-3454). Our results show that there are strong electrostatic effects within the NHC·H+ catalysed decarboxylation, and these dominate hydrogen bonding. At the same time, energy decomposition analyses and comparison between the original NHC·H+ catalyst and a truncated form reveal that stabilizing dispersion interactions are also critical, as is induction. We also show that the electrostatic effects and their associated catalytic effects can be further enhanced using charged functional groups.