Abstract
Hydrogenated N-phthaloyl-L-threonines (P-Thrs) and their dehydrated phthalimides (2-phthalimido-2-butenoic acids, P-BTEAs), novel plant growth regulators, were readily synthesized. N-(4, 5-Dichlorophthaloyl)-L-threonine and its dehydrated phthalimide also were synthesized. The synthetic P-Thrs and P-BTEAs had strong root growth-promoting activity for rice seedlings. The P-Thr activities were 1.6- to 2.2-fold the control value at 1×10-4M, and the activities of the dehydrated P-BTEAs were a little higher, 2.1- to 2.6-fold the control value at the same concentration. Hydrogenation of the benzene ring of the phthaloyl group reduced root growth-promoting activity. Interestingly, none of the hydrogenated and dichlorinated P-Thrs and P-BTEAs had significant root growth-promoting activity for seedlings of lettuce, Chinese cabbage and black gram, like that of the original N-phthaloyl-L-threonine (P-Thr, 5a) and its dehydrated phthalimide (P-BTEA, 6a).
