| abstract |
(57) [Summary] [PROBLEMS] To provide a method for industrially and efficiently producing monatins which can be expected as sweeteners such as sweeteners and foods and drinks. A condensate prepared by reacting an indoleacetic acid derivative having an appropriate protecting group with an acid halide of aspartic acid, preferably in the presence of a base, is decarboxylated and deprotected to give a stereoselective. A novel ketone derivative, such as 2-amino-5- (3-indolyl) -4-oxopentanoic acid, is subjected to cyanohydrination, preferably under basic conditions, and the resulting cyanohydrin derivative is subjected to basic conditions. Under the hydrolysis step, monatins are obtained. The obtained monatins are subjected to derivatization such as introduction of a protecting group, purified in the form of the obtained derivative, and then subjected to a deprotection reaction to remove the protecting group to obtain the desired high-purity. Monatins can be produced. Thus, monatins (monatin or its stereoisomer) The present invention provides an excellent production method of the above, an efficient production method of an important production intermediate therefor, and an important new intermediate thus obtained. |