Synthesis, absolute configuration and biological activity of both enantiomers of 2-(5,6-dichloro-3-indolyl)propionic acid: new dichloroindole auxins.
Racemic 2-(5,6-dichloro-3-indolyl)propionic acid (5,6-Cl2-2-IPA) was synthesized from 5,6-dichloroindole-3-acetic acid (5,6-Cl2-IAA) by successive esterification, methoxycarbonylation, methylation, and double hydrolysis. The racemate was converted to the diastereomeric esters of (S)-(-)-1-phenylethyl alcohol. These were separated by HPLC into two optically active diastereomers and then hydrolyzed with p-TsOH to the optically active enantiomers of 5,6-Cl2-2-IPA. The absolute configurations of both the 5,6-Cl2-2-IPA enantiomers were determined by comparing the 1H-NMR spectra of their diastereomeric (S)-(-)-1-phenylethyl esters with those of the diastereomeric (S)-(-)-1-phenylethyl esters of 2-(3-indolyl)propionic acid (2-IPA) whose absolute configurations are already known. There was no essential difference between (S)-(+)- and (R)-(-)-5,6-Cl2-2-IPA in hypocotyl growth-inhibiting activity toward Chinese cabbage, but their inhibitory activities were stronger than that of the potent mother auxin, 5,6-Cl2-IAA. No essential difference in the coleoptile elongating activity of Avena sativa was apparent for the enantiomers, this activity being about one-third that of 5,6-Cl2-IAA.
Katayama
M
M
Department of Chemistry, National Industrial Research Institute of Nagoya, Japan. katayama@nirin.go.jp
Kato
Y
Y
Marumo
S
S
D018554:Avena / Q000187:drug effects / Q000254:growth & development; D001937:Brassica / Q000187:drug effects / Q000254:growth & development; D018546:Hypocotyl / Q000187:drug effects / Q000254:growth & development; D007210:Indoleacetic Acids / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D011422:Propionates / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013237:Stereoisomerism
C432923:2-(5,6-dichloro-3-indolyl)propionic acid; D007210:Indoleacetic Acids; D007211:Indoles; D011422:Propionates