Computational chemistry has become important in organic synthesis as it provides a detailed understanding of molecular structures and properties and detailed reaction mechanisms.

G protein-coupled receptors (GPCRs) are major drug targets due to their ability to facilitate signal transduction across cell membranes, a process that is vital for many physiological functions to occur. The development of computational technology provides modern tools that permit accurate studies of the structures and properties of large chemical systems, such as enzymes and GPCRs, at the molecular level. The advent of multiscale molecular modeling permits the implementation of multiple levels of theories on a system of interest, for instance, assigning chemically relevant regions to high quantum mechanics (QM) level of theory while treating the rest of the system using classical force field (molecular mechanics (MM) potential). Multiscale QM/MM molecular modeling have far-reaching applications in the rational design of GPCR drugs/ligands by affording precise ligand binding configurations through the consideration of conformational plasticity. This enables the identification of key binding site residues that could be targeted to manipulate GPCR function. This review will focus on recent applications of multiscale QM/MM molecular simulations in GPCR studies that could boost the efficiency of future structure-based drug design (SBDD) strategies.

The total synthesis of the antitumor natural product thioamycolamide A has been accomplished in 19.1% overall yield featuring a diastereoselective sulfa-Michael reaction.

Kopsane alkaloids possess a complex heptacyclic scaffold and exhibit significant biological activities, including cholinergic, anti-inflammatory, and anti-cancer effects. While we previously reported PtCl₂-catalyzed [3 + 2] cycloaddition for their synthesis, the high cost and toxicity of platinum necessitate sustainable alternatives. In this study, we employed density functional theory (DFT) to investigate MCl₂ (M = Ni, Pd, and Pt) catalyzed [3 + 2] cycloaddition in Kopsane alkaloid synthesis. Our results indicate consistent reaction characteristics across all metals, with the second cyclization acting as the diastereoselectivity-determining step. The calculated energy gaps between transition states (TS2s) for NiCl₂, PdCl₂, and PtCl₂ were 5.57, 1.45, and 12.25 kcal/mol, respectively. These energy profiles suggest that NiCl₂ can achieve high diastereoselectivity similar to PtCl₂ due to its significant energy gap (> 4 kcal/mol). The implementation of this computational chemistry technique provides theoretical evidence that could help to improve the efficiency of the catalyst designing process.