The condensation of 3,4-dimethoxybenzaldehyde (I) with glycine (II) by means of KOH in hot methanol gives racemic threo-3-(3,4-dimethoxyphenyl)serine (III), which is acylated with N-(ethoxycarbonyl)phthalimide (IV) by means of Na2CO3 in water yielding the corresponding N-phthaloyl derivative (V). The reaction of (V) with AlCl3 and ethyl mercaptan in dichloromethane affords N-phthaloyl-3-(3,4-dihydroxyphenyl)serine (VI), which is deprotected with hydrazine in refluxing ethanol to racemic threo-3-(3,4-dihydroxyphenyl)serine (VII). The resolution of the racemic form (VII) is performed through its benzyloxy derivative.

The condensation of 3,4-dimethoxybenzaldehyde (I) with glycine (II) by means of KOH in hot methanol gives racemic threo-3-(3,4-dimethoxyphenyl)serine (III), which is acylated with N-(ethoxycarbonyl)phthalimide (IV) by means of Na2CO3 in water yielding the corresponding N-phthaloyl derivative (V). The reaction of (V) with AlCl3 and ethyl mercaptan in dichloromethane affords N-phthaloyl-3-(3,4-dihydroxyphenyl)serine (VI), which is deprotected with hydrazine in refluxing ethanol to racemic threo-3-(3,4-dihydroxyphenyl)serine (VII). The resolution of the racemic form (VII) is performed through its benzyloxy derivative.

The condensation of 3,4-dimethoxybenzaldehyde (I) with glycine (II) by means of KOH in hot methanol gives racemic threo-3-(3,4-dimethoxyphenyl)serine (III), which is acylated with N-(ethoxycarbonyl)phthalimide (IV) by means of Na2CO3 in water yielding the corresponding N-phthaloyl derivative (V). The reaction of (V) with AlCl3 and ethyl mercaptan in dichloromethane affords N-phthaloyl-3-(3,4-dihydroxyphenyl)serine (VI), which is deprotected with hydrazine in refluxing ethanol to racemic threo-3-(3,4-dihydroxyphenyl)serine (VII). The resolution of the racemic form (VII) is performed through its benzyloxy derivative.