The chemistry of 1-amino cyclopropanecarboxylic acid and its analogues

This work was undertaken to investigate a mechanism proposed for the in vivo conversion of ACC to ethylene.; Attempted isolation or trapping of the cyclopropanimine intermediate from the oxidative decarboxylation of ACC and its derivatives using hypochlorite as the oxidizing agent was not successful. Instead, ACC gave good yields of 3-hydroxypropionitrile and a small amount of ethylene. The secondary amino acids, N-methyl and N-benzyl ACC, gave 3-substituted propanamides plus ethylene. The tertiary amino acids, 1-(N,N-dimethylamino)-, 1-(N,N-dibenzylamino)-, and 1-(1-piperidino)cyclopropanecarboxylic acid gave complex mixtures and no ethylene. Though the formation of these ring-opened products could be explained by a route that involves a cyclopropanimine intermediate, a more probable alternative pathway is available.; 1-(1-Piperidino)cyclopropanol, a cyclopropanimine synthon, gave ethylene in 60-65% yield on treatment with hypochlorite. This reaction is a model for the second step of the mechanism proposed for ethylene formation from ACC.; 1-(1-Piperidino)cyclopropanecarboxylic acid yielded 1-(1-piperidino) cyclopropanol on treatment with phenyl iodosyl bis(trifluoroacetate) (PIFA). This reaction models the first step of the proposed mechanism for the formation of ethylene. cis-1-(1-Piperidino)cyclopropanecarboxylic acid-2,3-d{dollar}sb2{dollar} was decarboxylated to the corresponding carbinolamine by PIFA. Treatment of the labeled carbinolamine with hypochlorite yielded cis-ethylene-1,2-d{dollar}sb2{dollar}. With this result the relevance of the mechanism proposed for ethylene formation to the in vivo process was rendered unlikely, for ethylene formation in plants is not stereospecific and C-1 of ACC is converted to cyanide in plants.; Decarboxylation of ACC derivatives was demonstrated again when the azomethine ylid formed as an intermediate in the decarboxylation of ACC by ninhydrin was trapped with N-phenyl maleimide and with ninhydrin itself. Attempts to trap the azomethine ylid with methanol resulted in the formation of 2-(cyclopropylimino)-1,3-indanedione. Reaction of ACC and phenanthrenequinone resulted in the formation of 2-ethylphenanthro (9,10-d) oxazole, presumably formed by the opening of the cyclopropane ring of the expected 4-oxazoline derivative. Attempted decarbonylation of tertiary amino derivatives of ACC with POCl{dollar}sb3{dollar}, as an alternative pathway to the cyclopropaniminium salt, resulted in the formation of cyclopropanecarboxamides and the corresponding symmetrical anhydrides. (Abstract shortened with permission of author.)...