Cisselective

Cisselective refers to a type of chemical reaction where one stereoisomer, specifically the cis isomer, is preferentially formed over other possible stereoisomers, such as the trans isomer. This selectivity is crucial in organic synthesis as the stereochemistry of a molecule can significantly impact its physical, chemical, and biological properties. Many synthetic routes aim for cisselectivity to produce a desired compound with the correct spatial arrangement of atoms.

The achievement of cisselectivity often depends on the reaction mechanism and the nature of the reactants and reagents. For instance, catalytic hydrogenation of alkynes using poisoned catalysts like Lindlar's catalyst is a classic example of a cisselective reaction, yielding cis-alkenes. Other reaction types, such as certain cycloadditions or nucleophilic additions, can also exhibit cisselectivity under specific conditions. Understanding and controlling cisselectivity allows chemists to design efficient syntheses of complex molecules, including pharmaceuticals and natural products, where precise stereochemical control is paramount. The opposite of cisselective is transselective.