The reductive Heck cyclization of nonracemic benzylidene γ-butyrolactone is studied toward the asymmetric synthesis of aryltetralin lignans, where the stereochemistry of the benzylidene lactone is found to control the mode of cyclization. The Z-isomer undergoes mostly 6-endo-cyclization and provides the desired (−)-isopodophyllotoxin along with a minor amount of 5-exo-cyclized product, but the E-isomer goes through exclusively 5-exo-cyclization, leading to the undesired dihydroindenolactone compound instead of (−)-podophyllotoxin. The experimental results are well-supported by the DFT studies.

An efficient Ir(III)-catalyzed straightforward intermolecular N-arylation of acyclic aliphatic amides has been achieved using quinone diazide as a coupling partner. The reaction has been developed under simple and mild reaction conditions with a broad substrate scope. The bidentate picolinamide group is essential for successful transformation. Mechanistic studies and DFT calculations highlighted the migratory insertion-based pathway. The developed method exhibits different reactivities compared to the reactions of acyclic aliphatic amides using related diazo/azide congeners under Rh(III)/Ir(III) catalysis.

We have explored the chemical space of BAl4Mg−/0/+ for the first time and theoretically characterized several isomers with interesting bonding patterns. We have used chemical intuition and a cluster building method based on the tabu-search algorithm implemented in the Python program for aggregation and reaction (PyAR) to obtain the maximum number of possible stationary points. The global minimum geometries for the anion (1a) and cation (1c) contain a planar tetracoordinate boron (ptB) atom, whereas the global minimum geometry for the neutral (1n) exhibits a planar pentacoordinate boron (ppB) atom. The low-lying isomers of the anion (2a) and cation (3c) also contain a ppB atom. The low-lying isomer of the neutral (2n) exhibits a ptB atom. Ab initio molecular dynamics simulations carried out at 298 K for 2000 fs suggest that all isomers are kinetically stable, except the cation 3c. Simulations carried out at low temperatures (100 and 200 K) for 2000 fs predict that even 3c is kinetically stable, which contains a ppB atom. Various bonding analyses (NBO, AdNDP, AIM, etc.) are carried out for these six different geometries of BAl4Mg−/0/+ to understand the bonding patterns. Based on these results, we conclude that ptB/ppB scenarios are prevalent in these systems. Compared to the carbon counter-part, CAl4Mg−, here the anion (BAl4Mg−) obeys the 18 valence electron rule, as B has one electron fewer than C. However, the neutral and cation species break the rule with 17 and 16 valence electrons, respectively. The electron affinity (EA) of BAl4Mg is slightly higher (2.15 eV) than the electron affinity of CAl4Mg (2.05 eV). Based on the EA value, it is believed that these molecules can be identified in the gas phase. All the ptB/ppB isomers exhibit π/σ double aromaticity. Energy decomposition analysis predicts that the interaction between BAl4−/0/+ and Mg is ionic in all these six systems.

We studied the steps in the formation of active palladium catalyst species from palladium acetate dimer employing density functional theory calculations. We explored the possible pathways with an automated reaction search and studied the kinetics with stochastic simulation analysis. The dimeric form of palladium acetate is considered a resting state of the catalyst. Our reaction search starting from the dimeric form by sequential ligand addition resulted in experimentally observed monomeric species. We analyzed the bonding in the palladium acetate dimer and the role of Pd in the stability of the dimeric species. We implemented the Gillespie stochastic simulation algorithm to gain more insights into multichannel reaction paths and applied it to the degradation pathways. The analysis of the thermodynamic and kinetic data for these degradation pathways suggests that the dimeric form of the catalyst can be a potential catalytic precursor in the palladium acetate-catalyzed coupling reactions under the experimental reaction conditions.

Chemical intuition yields the second low-lying isomer after AUTOMATON found the global minimum and few other low-lying isomers.