Derivatives of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid

The following derivatives of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid have been prepared in their (S)-form and as racemates: hydrochloride of methyl ester, N-carboxy anhydride, and N-acetyl derivative. All the substances were fully characterised by elemental analyses, H-1 and C-13 NMR spectra, and optical rotation, as the case may be; the M-carboxy anhydride was also characterised by means of X-Ray diffraction. Also identified was the intermediate of the reaction of the title acid with phosgene, the N-chlorocarbonyl derivative, and the respective methyl ester was prepared. The dioxopiperazine of the title acid was prepared and characterised both in pure (S,S)-form and in the form of a mixture of two racemates. The optically pure dioxopiperazine was prepared by a reaction of the N-carboxy anhydride in solid phase.