Patent ID: 6951955

Claim:
A process for the preparation of a compound of Formula I: wherein: R 1 and R 2 are independently selected from H, straight chain alkyl of 1 to 4 carbon atoms, halogen and alkoxy of 1 to 4 carbon atoms; R 3 is straight chain alkyl of 1 to 4 carbon atoms; R 4 is straight chain alkyl of 1 to 4 carbon atoms and branched chain alkyl of 3 to 4 carbon atoms; R 5 is straight chain alkyl of 1 to 4 carbon atoms; comprising: a) treating a nitrile of the formula: with a reducing agent followed by acid hydrolysis to obtain an aldehyde of the formula: b) reacting the aldehyde (step a) with alkali metal cyanide in the presence of an alkyl amine of the formula R 5 NH 2 to obtain nitrile of the formula: c) hydrolyzing the nitrile (step b) with an alkali metal hydroxide to give an amide of the formula: d) reacting the amide (step c) with an organic carbonate, of the formula O[CO 2 R 4 ] 2 wherein each R 4 is taken independently in the presence of dimethylaminopyridine (DMAP) to obtain a triblocked amide of the formula: e) hydrolyzing triblocked amide (step d) with an alkali metal hydroxide to give racemic blocked amine of the formula: f) reacting racemic blocked amine (step e) with a resolving base (NH 2 -resolving base) to obtain a resolved blocked amine salt of the formula: and g) treating the resolved blocked amine salt with aqueous alkali metal hydroxide and acidifying with acid to give a compound of Formula I: