Synthesis and growth regulatory activity of phenoxy substituted (benzo)imidazo[2,1-b][1,3]-thiazines

Abstract

A number of new 6-phenoxy-6,7-dihydro-5H-imidazo[2,1-b][1,3]thiazines 4a–g and their benzoannelated derivatives 4h–l were synthesized by the interaction of substituted 2-chlorobenzenes with 3-hydroxy(benzo)imidazo[2,1-b][1,3]thiazines in mild reaction conditions with the yields of 62–69%. The structure of the target compounds was proven by the results of 1H NMR and 13C NMR spectrometry and LC-MS. All newly synthesized compounds were studied for the features of the physiological development of seedlings of the dicotyledonous plant Cucumis sativus. According to the results of the experiment, it was found that 3-сhloro-4-[(3,4-dihydro-2H-benzo[4,5]imidazo[2,1-b][1,3]thiazin-3-yl)oxy]benzonitrile 4k and 4-сhloro-3-[(6,7-dihydro-5H-imidazo[2,1-b][1,3]thiazin-6-yl)oxy]benzonitrile 4e have the most stable inhibitory effect; and 6-(2,4-dinitrophenoxy)-6,7-dihydro-5H-imidazo[2,1-b][1,3]thiazine 4c and 3-(2,4-dinitrophenoxy)-3,4-dihydro-2H-benzo[4,5]imidazo[2,1-b][1,3]thiazine 4j show the best growth stimulating activity at the concentration of 0.0001%.