Synthesis of Methyl and Ethyl 3-Alkylthiazolidine-4(R)-carboxylates and Their Roots Inhibition of the Growth of Brassica campestris

Methyl and ethyl 3-alkylthiazolidine-4(R)-carboxylates (1–6 and 7–12), which were newly synthesized, inhibited growth of the roots of Brassica campestris L. subsp. rapa Hook fil. et Anders. Of the methyl esters, methyl 3-methylthiazolidine-4(R)-carboxylate (2) was the strongest inhibitor. Of the ethyl esters, ethyl 3-methylthiazolidine-4(R)-carboxylate (8) was the strongest inhibitor. The chlorophyll concentration in the cotyledons of plants treated with any of the compounds, except for 7, was decreased.