Regio and stereoselectivity in ionic cycloadditions

Studies of Regio- and Stereoselectivity

DFT Studies on the Stereoselectivity of α-Silyloxy Diazoalkane Cycloadditions.

The intramolecular [3+2] cycloaddition (32CA) of alkene-tethered α-silyloxydiazoalkanes provides variable stereoselectivity in generating bicyclic pyrazolines where the silyloxy group is either syn or anti to the newly formed pyrazoline ring. To elucidate the origin of the stereoselectivity, density functional theory (DFT) calculations were carried out for the energy of each transition state st...

Species differences in the regio- and stereoselectivity of 1-nitronaphthalene metabolism.

1-Nitronaphthalene (1-NN) is a mutagenic nitroaromatic that has been detected in emissions from both heavy- and light-duty diesel engines, as well as in urban airborne particles. 1-NN is a cytochrome P450-bioactivated, nonciliated bronchiolar epithelial (Clara) cell cytotoxicant. Our recent studies demonstrated that 1-NN was metabolized by rat lung and liver microsomal enzymes to six 1-NN GSH c...

Aspartyl Oxidation Catalysts That Dial In Functional Group Selectivity, along with Regio- and Stereoselectivity

A remarkable aspect of enzyme evolution is the portability of catalytic mechanisms for fundamentally different chemical reactions. For example, aspartyl proteases, which contain two active site carboxylic acid groups, catalyze the hydrolysis of amide bonds, while glycosyltransferases (and glycosyl hydrolases), which often also contain two active site carboxylates, have evolved to form (or break...

Digging deeper into CYP3A testosterone metabolism: kinetic, regio- and stereoselectivity differences between CYP3A4/5 and CYP3A7