Improved Methodology for the Preparation of Chiral Amines

It should be clear that the term chiral drug does not indicate that the drug is marketed as a
single isomer it may be a racemic or unequal mixture of isomers. Through investigating the
origin of chirality it was revealed that the concept was introduced long ago. Archimedes
designed Archimedean water screw and studied its chiral structure. Dominique Arge (1811)
discovered the rotation of plan polarized light in quartz crystal. Later the French chemist Jean
Baptiste Biot was the first to introduce the modern concept of chirality when he discovered
rotation of light in a sugar solution. [5]
The major breakthrough in understanding the concept of chirality and its significance in
chemistry was achieved by Louis Pasteur through recrystallization of sodium ammonium
tartrate (optically inactive). He noticed that the crystals were of two types which he
physically separated. The two types of crystals were optically active, but rotated the plane of
polarized light in the opposite directions. He proposed that the molecules came in two forms,
“left handed” and “right handed”. Together, the mixture of the two forms is optically
inactive. This finding prompted his famous statement that the universe is chiral (l’univers est
dissymme´trique). [6]
Later Van’t Hoff, a Dutch young scientist proposed that the carbon atom is attached to four
different substituents in space having a tetrahedral arrangement. This proposition was faced
by strong opposition from scientists all over the world. Later they discovered that his
proposed shape of the molecule was absolutely right and he was awarded the first noble prize
in chemistry for his work. [7] Chirality is manifested by centre of dissymmetry, but it can also
be represented in axes or planes of dissymmetry. [8]
1.2. Isomers and Isomerism
Isomerism is the phenomenon of two or more compounds having the same number and kind
of atoms. [9] Isomers can be subdivided into structural isomers, the difference between
isomers is due to a different structural arrangements of the atoms that form molecules, e.g.
butane and isobutene. The other division is stereoisomers, the isomers have the same
structural formula, but differ in the spatial arrangement of atoms. [9]
There are two types of stereoisomers:
2