In
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, ...
, ''endo''–''exo'' isomerism is a special type of
stereoisomerism
In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...
found in
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...
s with a
substituent on a
bridged ring system. The prefix ''endo'' is reserved for the
isomer with the substituent located closest, or "''syn''", to the longest bridge. The prefix ''exo'' is reserved for the isomer with the substituent located farthest, or "''anti''", to the longest bridge. Here "longest" and "shortest" refer to the number of atoms that comprise the bridge. This type of
molecular geometry
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that dete ...
is found in
norbornane
Norbornane (also known as bicyclo .2.1eptane) is an organic compound and a saturated hydrocarbon with chemical formula C7H12. It is a crystalline compound with a melting point of 88 °C. The carbon skeleton is derived from cyclohexane ring with a ...
systems such as
dicyclopentadiene
Dicyclopentadiene, abbreviated DCPD, is a chemical compound with formula C10H12. At room temperature, it is a white brittle wax, although lower purity samples can be straw coloured liquids. The pure material smells somewhat of soy wax or camphor ...
.
The terms ''endo'' and ''exo'' are used in a similar sense in discussions of the
stereoselectivity in Diels–Alder reactions.
References
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{{Navbox stereochemistry
Stereochemistry