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A detailed account for the development procedure that address several important factors related to epoxide-opening cascades which offer the potential to construct complex polyether natural products is presented. The key centerpiece in the method is a trimethylsilyl (Si[Me.sub.3]) group that serves several purposes and leaves no trace of itself at the end of the reaction scope.

The reactions of enantiopure (SR)-[(p-tolylsulfinyl)methyl]-p-quinol with ArAl[Me.sub.2] reagents have allowed a highly diastereoselective 1,4-addition of the aryl group with an efficient desymmetrization of the prochiral cyclohexadienone moiety. The asymmetric synthesis of phenyl-substituted polyoxygenated cyclohexane derivatives is achieved by combining this reaction with a stereoselective reduction and elimination of the [beta]-hydroxysulfide to recover a carbonyl group and a stereoselective epoxidation.

The regiocontrolled synthesis of a novel family of enantiopure azobenzenes where the ortho or meta position of the sulfoxide with respect to the N[double bond]N group, is able to produce a chiral perturbation on the E or Z isomers, is reported. The different values of specific chiral entities have reflected the existence of distinct chiral entities in the photostationary states and the reversible changes occurring between different conformational states can be used in the photocontrol of many molecular switches.

The first epoxide ring-opening cascades that afford ladder polyethers containing no directing groups at the end of the cascade, and overcome the inherit bias for formation of a tetrahydrofuran (5-exo) over tetrahydropyran (6-endo) in the opening of a trans-disubstituted epoxide by a pendant hydroxyl group are reported. It is concluded that the combination of a Me(sub 3)Si group, a Bronsted base, a fluoride source, and a hydroxylic solvent enables the first construction of the tetrahydropyran tetrad.

Azobenzene is prepared by the direct reaction between quinone bisacetals and arylhydrazines. The reaction accelerate strongly with the presence of catalytic amounts of cerium ammonium nitrate

Cyanide is a hazardous and detrimental chemical that causes the inactivation of the respiration system through the inactivation of cytochrome c oxidase. Because of the limitation in the number of cyanide-degrading enzymes, there is a great demand to design and introduce new enzymes with better functionality. This study developed an integrated method of protein-homology-modelling and ligand-docking protein-design approaches that reconstructs a better active site from cyanide hydratase (CHT) structure. Designing a mutant CHT (mCHT) can improve the CHT performance. A computational design procedure that focuses on mutation for constructing a new model of cyanide hydratase with better activity was used. In fact, this study predicted the three-dimensional (3D) structure of CHT for subsequent analysis. Inducing mutation on CHT of Trichoderma harzianum was performed and molecular docking was used to compare protein interaction with cyanide as a ligand in both CHT and mCHT. By combining multiple designed mutations, a significant improvement in docking for CHT was obtained. The results demonstrate computational capabilities for enhancing and accelerating enzyme activity. The result of sequence alignment and homology modeling show that catalytic triad (Cys-Glu-Lys) was conserved in CHT of Trichoderma harzianum. By inducing mutation in CHT structure, MolDock score enhanced from −18.1752 to −23.8575, thus the nucleophilic attack can occur rapidly by adding Cys in the catalytic cavity and the total charge of protein in pH 6.5 is increased from −6.0004 to −5.0004. Also, molecular dynamic simulation shows a stable protein-ligand complex model. These changes would help in the cyanide degradation process by mCHT. [ABSTRACT FROM AUTHOR]

Review: recent methodologies for the simultaneous formation of C-CF3 and C-C or C-heteroatom bonds by formal addition reactions to alkenes; 70 refs. [ABSTRACT FROM AUTHOR]