It is a stereoisomer and pseudo-enantiomer of cinchonine. It is a stereoisomer and pseudo-enantiomer of cinchonidine. The stereoisomer of oleic acid is called elaidic acid or trans-9-octadecenoic acid. Therefore, each mirror pair and each non-chiral stereoisomer may be given a specific monosaccharide name. Levoamphetamine is the levorotatory stereoisomer of the amphetamine molecule. Upon subsequent removal of the auxiliary, the desired aldol stereoisomer is revealed. It is a stereoisomer of quinine, originally derived from the bark of the cinchona tree. In the United States, zopiclone is not commercially available, although its active stereoisomer, eszopiclone is. This product then undergoes transamination and methylation to form ephedrine and its stereoisomer, pseudoephedrine. The second stereoisomer (2"S",3"S"), which is rarely present in nature, is called -allothreonine. Merck in-licensed L-"threo"-isoleucyl thiazolidide and its "allo" stereoisomer. Endrin is a stereoisomer of dieldrin. The pseudoequatorial positions of both "appendages" in the starting material lead to the observed stereoisomer. The other stereoisomer, "i.e. trans" or, better, (1"r", 4"r"), is called epiprephenic. Aldoses are commonly referred to by names specific to one stereoisomer of the compound.