The historically relevant D/L system
relates chiral molecules to the D and
L enantiomers of glyceraldehyde. The stereodescriptors
D and L are accepted in CurlySMILES
notations for molecules with one asymmetric atom:
OCC{D}(O)C=O
OCC{L}(O)C=O
D-glyceraldehyde
L-glyceraldehyde
The systematic name of D-glyceraldehyde is
(R)-2,3-dihydroxypropanal: OCC{D}(O)C=O and
OCC{R}(O)C=O encode the same enatiomer.
The systematic name of L-glyceraldehyde is
(S)-2,3-dihydroxypropanal: OCC{L}(O)C=O and
OCC{S}(O)C=O encode the same enatiomer.
Another example is L-cysteine with the systematic name
(R)-2-amino-3-sulfanylpropanoic acid: O=C(O)C{L}(N)CS and
O=C(O)C{R}(N)CS encode the same enatiomer.
Molecules with more than one stereogenic center should always be
encoded by using the R and S stereodescriptors,
illustrated for (2R,3R)-2,3,4-trihydroxybutanal,
commonly known as D-erythrose: O=CC{R}(O)C{R}(O)CO
B. Testa:
Principles of organic stereochemistry. Marcel Dekker,
New York and Basel,
1979.
[2]
D. Hellwinkel:
Systematic Nomenclature of Organic Chemistry. Springer-Verlag,
Berlin und Heidelberg, Germany,
2001.
[3]
A. Drefahl:
CurlySMILES: a chemical language
to customize and annotate encodings of molecular and
nanodevice structures.
J. Cheminf.2011, 3:1;
doi:
10.1186/1758-2946-3-1
.