NEW MATERIAL:A compound expressed by the formula and salt of the compound (R is H, protecting group of amino group; Y is lower alkyl, phenyl, phenylalkyl, hydroxyalkyl, hydroxyphenylalkyl or phenylalkyloxyalkyl; X is sulfo, mesyl, tosyl, acetylthio or halogen).

EXAMPLE: An (S)-2-(N-t-butoxycarbonyl)aminopropane-1-ol.

USE: Used as a growth-regulating substance of plants.

PREPARATION: A compound expressed by the formula having OH as X is used as a raw material and subjected to mesylation by reacting with methanesulfonyl chloride in a solvent such as methylene chloride in the presence of a base such as triethylamine, then subjected to tosylation by using toluenesulfonyl chloride, etc., thus halogenated by hydrogen bromide, etc., and thioated by thioacetic acid, then resultant compound is sulfonated by reacting with sodium sulfite.