Silanes: Compounds similar to hydrocarbons in which a tetravalent silicon atom replaces the carbon atom. They are very reactive, ignite in air, and form useful derivatives.Indolizidines: Saturated indolizines that are fused six and five-membered rings with a nitrogen atom at the ring fusion. They are biosynthesized in PLANTS by cyclization of a LYSINE coupled to ACETYL COENZYME A. Many of them are naturally occurring ALKALOIDS.Quinolizidines: Saturated quinolizines that are two fused six-membered rings with a nitrogen atom at the ring fusion. They are biosynthesized in PLANTS by cyclization of a LYSINE coupled to CADAVERINE. Many of them are naturally occurring ALKALOIDS.Stereoisomerism: The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Catalysis: The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.