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A novel practical method for the synthesis of N-methyl-DL-aspartic acid 1 (NMA) and new syntheses for N-methyl-aspartic acid derivatives are described. NMA 1, the natural amino acid was synthesized by Michael addition of methylamine to dimethyl fumarate 5. Fumaric or maleic acid mono-ester and -amide were regioselectively transformed into beta-substituted aspartic acid derivatives. In the cases of maleamic 11a or fumaramic esters 11b, the alpha-amide derivative 13 was formed, but hydrolysis of the product provided N-methyl-DL-asparagine 9 via base catalyzed ring closure to DL-alpha-methylamino-succinimide 4, followed by selective ring opening. Efficient methods were developed for the preparation of NMA-alpha-amide 13 from unprotected NMA via sulphinamide anhydride 15 and aspartic anhydride 3 intermediate products. NMA diamide 16 was prepared from NMA dimethyl ester 6 and methylamino-succinimide 4 by ammonolysis. Temperature-dependent side reactions of methylamino-succinimide 4 led to diazocinone 18, resulted from self-condensation of methylamino-succinimide via nucleophyl ring opening and the subsequent ring-transformation.

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Some cyclic chalcone analogues [E-2-(X-benzylidene)-1-indanones, -tetralones, and -benzosuberones], on-plate UV light-catalyzed formation of new chromatographic spots, can be observed during thin-layer chromatography (TLC). Gas chromatographic (GC) analysis of selected derivatives indicates the formation of one new substance in each case. GC coupled with mass spectrometry and 1H NMR analysis of the samples reveals that the compounds formed are the respective Z-2-(X-benzylidene)-1-indanones, -tetralones, and -benzosuberones. Two-dimensional TLC shows that the E/Z isomerization is a reversible process. By means of the RP-TLC, the logarithm of n-octanol-water partition coefficient (log P) values of E- and Z-isomeric pairs of selected 2-(X-benzylidene)-1-benzosuberones is determined. The Z-isomers are less lipophilic than the E-isomers.