1. Field of the Invention
The present invention relates to processes for the preparation of optically active amines or salts thereof and processes for the preparation of optically active imines. The invention also relates to novel optically active amines and salts thereof and to novel optically active imines.
2. Description of the Related Art
Certain optically active amines are known in the art as intermediates for medical drugs and agricultural chemicals. For example, an optically active 7-amino-5-azaspiro[2.4]heptane is a compound useful as an intermediate for synthetic antimicrobial agents that have high antibacterial activities.
Such an optically active 7-amino-5-azaspiro[2.4]heptane has been prepared by certain processes typically described in Japanese Unexamined Patent Application Publications No. 11-240867 and No. 11-240868. In these processes, an oxo group at the 7-position of a precursor 5-benzyl-4,7-dioxo-5-azaspiro[2.4]heptane is oximated with hydroxylamine, and an oxo group at the 4-position and a hydroxyimino group at the 7-position are reduced to yield 7-amino-5-benzyl-5-azaspiro[2.4]heptane, the 7-amino-5-benzyl-5-azaspiro[2.4]heptane is then condensed with an optically active carboxylic acid and is converted into a 5-benzyloxycarbonyl derivative, the resulting diastereomers are separated and are deprotected to thereby yield an optically active 7-amino-5-azaspiro[2.4]heptane.
These publications also describe a process for the preparation of an optically active 7-amino-5-azaspiro[2.4]heptane derivative, in which an optically active 1-phenylethyl group is introduced, instead of the benzyl group, at the 5-position of 5-benzyl-4,7-dioxo-5-azaspiro[2.4]heptane, the oxo group at the 7-position of the resulting compound is converted into an amino group, and the resulting diastereomers are separated to thereby yield the target compound.
In all of these processes, however, diastereomers are once prepared synthetically and are then subjected to resolution. The processes are thereby low in yields and are not efficient for the preparation of an optically active 7-amino-5-azaspiro[2.4]heptane.