It is critical that the configuration of the chiral carbon is (S) because (R) is inactive.
However, unlike hemiacetals, lactones do not have a chiral anomeric carbon, and they cannot form glycosidic linkages.
In a free radical substitution reaction, if the formation of the free radical takes place at a chiral carbon, then racemization is almost always observed.
A chiral carbon is often denoted by C*.
For this reason, there are only three distinct 3-ketopentose stereoisomers, even though the molecule has two chiral carbons.
Like flipping a coin - producing only a head or a tail, there can be only two arrangements about the chiral carbon.
Flavanols possess two chiral carbons, meaning four diastereoisomers occur for each of them.
Organic compounds that contain a chiral carbon usually have two non-superimposable structures.
In the case of the phenyltropanes, although there are four chiral carbons, there are only eight possible isomers to consider.
Labetalol has two chiral carbons and consequently exists as four stereoisomers.