Abstract: A propionic acid thiol ester derivative having the formula: ##STR1## wherein R.sub.1 is a cyano group, a trifluoromethyl group, a halogen atom or a nitro group,R.sub.2 is a hydrogen atom, a halogen atom or a cyano group,R.sub.3 is a thiazolin-2-yl group or a benzothiazol-2-yl group, andA is a methine group or a nitrogen atom.

Abstract: 1,2,4-oxadiazole derivatives having selective herbicidal action in controlling broad leaf weeds and cyperaceous weeds without causing phytotoxicity to geraminous crop plants having the formula: ##STR1## wherein A is a methine group or a nitrogen atom; R.sub.1 is a chlorine atom or a methyl group; when A is a methine group, R.sub.2 is a hydrogen atom if R.sub.1 is a methyl group, and a hydrogen atom or a methyl group if R.sub.1 is a chlorine atom, and when A is a nitrogen atom, R.sub.2 is a hydrogen atom; R.sub.3 is a hydrogen atom, an alkyl group having from 1 to 11 carbon atoms, a benzyl group unsubstituted or substituted by chlorine or methoxy; a phenoxymethyl group unsubstituted or substituted by chlorine or methyl, or a lower alkoxyalkyl group.

Abstract: A propionic acid thiol ester derivative having the formula: ##STR1## wherein R.sub.1 is a cyano group, a trifluoromethyl group, a halogen atom or a nitro group, R.sub.2 is a hydrogen atom, a halogen atom or a cyano group, R.sub.3 is a thiazolin-2-yl group or a benzothiazol-2-yl group, and A is a methine group or a nitrogen atom.

Abstract: The invention provides a novel and efficient method for the elimination of protecting groups, e.g. benzyloxycarbonyl group, from a protected amino acid, peptide or derivative thereof having at least one functional group protected by a protecting group, e.g. a lower alkyl ester of N-benzyloxycarbonyl-.alpha.-L-aspartyl-L-phenylalanine by catalytic hydrogen reduction to produce free amino acid, peptide or derivative thereof. In contrast to the conventional procedures in which the reaction is carried out in a solvent dissolving both the starting compound and the product compound or a solvent dissolving the starting compound but not dissolving the product compound, the inventive method utilizes a binary two-phase reaction medium composed of water and an organic solvent not freely miscible with water such as toluene.

Abstract: A method for purifying an .alpha.-L-aspartyl-L- phenylalanine lower alkyl ester containing impurities. The .alpha.-L-aspartyl-L-phenylalanine lower alkyl ester is brought into contact with a Cl-type anion exchange resin in an aqueous medium to have the impurities adsorbed by the anion exchange resin. The impurities contained in the .alpha.-L-aspartyl-L-phenylalanine lower ester, particularly diketopiperazine and .alpha.-L-aspartyl-L-phenylalanine are selectively and easily removed. The desired matter thus can be easily recovered and disposal of waste liquid, etc. can also be carried out without difficulty.

Abstract: An improvement in a method for manufacturing dipeptides from an N-substituted aspartic acid and a phenylalanine lower alkyl ester. The two starting materials are allowed to react with each other in the presence of an immobilized metallo-proteinase in an organic solvent immiscible with water. The enzyme can be recovered for reuse thereof. The loss of materials due to the hydrolysis of the phenylalanine lower alkyl ester is reduced, so that use of the phenylalanine lower alkyl ester in a nearly stoichiometric quantity suffices for the reaction to ensure an improved yield and reduction in cost of industrial production.