Synthesis and Properties of New 4-Oxo-4,5-dihydro-1,3-oxazolium Perchlorates

D-Pantoic acid amide obtained by treatment of D-(–)-pantolactone with ammonia reacted with acetic anhydride in the presence of perchloric acid to give 5-[2-(acetoxy)-1,1-dimethylethyl]-2-methyl-4-oxo- 4,5-dihydro-1,3-oxazolium perchlorate. Reaction of the latter with aromatic aldehydes afforded 2-(2- arylethenyl)-4-oxo-4,5-dihydro-1,3-oxazolium perchlorates which showed no appreciable growth-regulating activity but clearly exhibited antidotal activity against 2,4-dichlorophenoxyacetic acid (2,4-D herbicide).