Triterpenes are natural products of plants that can defend against microorganisms and various stresses. Oxidosqualene cyclase (OSC), the key rate-limiting enzyme triterpene biosynthetic pathway, catalyzes 2,3-oxidosqualene into sterols triterpenes with different skeletons through chair–boat–chair (CBC) conformation or chair–chair–chair (CCC) conformation. They were expanded in mainly by tandem ...

the 1h and natural-abundance 13c-nmr spectra of 1-thiacyclooctan-3-one (1) have been measured from 25 to -100°c. coalescence is observed in the 1h-nmr spectra of (1) at about -80°c, and attributed to ring inversion in a boat-chair conformation, which is the predominant conformation of (1). the free energy of activation (dg¹) for this process is 9.2±0.2 kcal/mol. the 13c-nmr spectra of (1) is te...

ab initio calculations at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g*for total energy calculation are reported for z-cyclooctene (1). the most favorable conformation of 1 is theunsymmetric boat-chair (1-bc) geometry. potential energy profiles for two different boat-chair/boat-chairinterconversion processes were calculated. the process via a chair transition sta...

Ab initio calculation at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G* for a single point total energy calculation are reported for the important energyminimumconformations and transition-state geometries of of cyclodeca-1,2,3-triene (1). The mostfavorable conformation of 1 is a unsymmetrical twist-chair (1-TC) structure. Degenerateinterconversion of 1-TC with it...

The 1H and natural-abundance 13C-NMR spectra of 1-thiacyclooctan-3-one (1) have been measured from 25 to -100°C. Coalescence is observed in the 1H-NMR spectra of (1) at about -80°C, and attributed to ring inversion in a boat-chair conformation, which is the predominant conformation of (1). The free energy of activation (DG¹</s...

ab initio calculation at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g* for a single point total energy calculation are reported for the important energyminimumconformations and transition-state geometries of of cyclodeca-1,2,3-triene (1). the mostfavorable conformation of 1 is a unsymmetrical twist-chair (1-tc) structure. degenerateinterconversion of 1-tc with it...

The enzymatic cyclization reaction of polyprenoid C(33) by squalene-hopene cyclase (SHC) was investigated with the intention of creating an unnatural hexacyclic compound. The enzymatic products consisted of mono-, bi-, tri-, tetra- and pentacyclic skeletons; however, hexacyclic products were not generated, contrary to our expectations. The absence of a hexacyclic skeleton indicated that the ent...

Ab initio calculations at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G*for total energy calculation are reported for Z-cyclooctene (1). The most favorable conformation of 1 is theunsymmetric boat-chair (1-BC) geometry. Potential energy profiles for two different boat-chair/boat-chairinterconversion processes were calculated. The process via a chair transition sta...

The Cover Feature illustrates the pathways undergone by ditellurocines from solid state (represented stones) to solution water cascade). Once ditellurocine crystals/stones roll down in cascade, metamorphosis occurs, cubic-like arrangement a caterpillar (less stable chair conformation) then lying butterfly (transition state) and flying (more boat conformation). More information can be found Full...

Ab initio calculations at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G* for a single point total energy calculation are reported for the importantenergy-minimum conformations and transition-state geometries of 1, 3-diazacyclohepta-1, 2-diene (2) and 1, 3-diazacycloocta-1, 2-diene (3). The C2 symmetric twist-chair (2-TC)conformation of 2 is calculated to be 7.4 kJ...