Synthesis
a) Salicylaldehyde and benzylamine (molar ratio 1:1) were dissolved in ethanol and the mixture was refluxed for 2 hours. The reaction was stirred at room temperature for an additional 2 h. The solvent was removed under reduced pressure to give the imine in quantitative yield.
b) To the above obtained imine was added anhydrous tetrahydrofuran (THF), trimethylcyanosilane (TMSCN) was slowly added dropwise with a molar ratio iminization: TMSCN of 1: 3. The reaction mixture was stirred at room temperature for 40 h. The reaction mixture was added to a solution of saturated ammonium chloride followed by (NH4Cl), extracted with ether, the ether phase was washed with water, and finally dried with magnesium sulphate, and solvent was removed under vacuum, and it was -aminonitrile is obtained quantitatively as an oil.
c) The obtained -aminonitrile is heated in concentrated hydrochloric acid at 60-70C for 3 hours. Thereafter, the crude oil was allowed to cool and dried under reduced pressure. After drying, the residue was suspended in acetone, filtered and dried to give N-benzyl-2-hydroxyphenylglycine hydrochloride as a powdered solid in 97% yield.
d) To a methanolic solution of (15% by weight in mass of substrate)-benzyl-2-hydroxyphenylglycine N was added a solution of hydrochloric acid in Pd (c) and then carried out under hydrogen pressure (50 psi) for 16 hours. The crude product was filtered and the solvent was removed under reduced pressure to give 2-hydroxyphenylglycine in 96% yield.
