Studies on the Chemical Constitunts of Tea

Previously, one of the authors discovered a new amide in the water extract of Japanese green tea and named it theanine which was assumed to be L-glutamic acid γ-ethyl amide. Now we attempted to synthesize it according to the following scheme. L-Glutamic acid→L-glutamic acid γ-ethyl ester →N-cbz-L-glutamic acid γ-ethyl ester →N-cbz-L-glutamic acid γ-ethyl amide →L-glutamic acid γ-ethyl amide. L-Glutamic acid γ-ethyl amide obtained here had m. p. 217_??_218° (decompose) and [α]20D=+7.0. The mixture with natural theanine (m. p. 217°) showed no depression of its m. p. Their Cusalts were also completely identical. Therefore, it is provedd that natural theanine is L-glutamic acid γ-ethyl amide itself.