SYNTHESIS AND PROPERTIES OF C-1-AZIDO-ABA

Article abstract of DOI:10.1016/0031-9422(93)85222-D

The acyl azido derivative of ABA has been synthesized in high yield via a mixed anhydride.It is stable in most organic solvents but rearranges in water (t_1/2 of 30 min at 30 deg C) to yield 1'-hydroxy-4'-oxo-α-ionone, presumably via an isocyanate intermediate.Photolysis of (+/-) RS-azido-ABA in a 1percent solution of bovine serum albumin with low intensity UV_254nm light gave labelled bovine serum albumin (BSA).Racemic 1-azido-ABA inhibited wheat embryo growth with about 10percent the efficacy of racemic ABA.Racemic 1-azido-ABA was resolved into its enantiomers on a chiralcel HPLC column and both enantiomers were bioassayed.The (+)S-enantiomer caused stomatal closure and inhibited growth of Lemna gibba with about 10percent of the potency of ABA but the (-)R-enantiomer was inactive in both the stomatal closure and Lemna gibba bioassays.It is suggested that in one of the two canonical forms of the azide the α-nitrogen atom carries the negative charge in the same position as the carboxyl group of ABA and so is able to substitute for it. Key Word Index: Abscisic acid; indole acetic acid; gibberellin; azide; bioassay; photoaffinity labelling; receptor.