[New alkylated derivates and dissociation constans of 3-hydroxy-1,2-benzisoxazole]
Abstract:
In the reactions of 3-hydroxy-1,2-benzisoxazole (BIO) and its 5-Cl and 6-Cl derivatives with ethyl bromoacetate were obtained the mixtures of O- and N- substituted esters but 7-NO2-BIO formed only O-ester. The products of N-aminomethylation of 5-NO2-BIO were active against Trichomonas vaginalis. The structures of pure compounds have been confirmed by elementary analysis and IR spectrometry. Determinations of dissociation constants (pKa) of BIO, 5-Cl-BIO, 6-Cl-BIO, 7-Cl-BIO, 5-F-BIO, 5-NO2-BIO, 7-NO2-BIO by potentiometric titration method were described. Investigated compounds have two values of ionisation constants except the nitro derivatives, this is the confirmation of equilibrium 3-hydroxy-1,2-benzisoxazole <==> 1,2-benzisoxazolinone-3.
Related Concept Videos
Hydroboration-Oxidation of Alkenes
Reactions at the Benzylic Position: Oxidation and Reduction
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Ketones with Nonenolizable Aromatic Aldehydes: Claisen–Schmidt Condensation
As the self-condensation of ketones is generally not favored in basic conditions, the self-condensed products do not form in the reaction between ketones and benzaldehyde. The general reaction of Claisen–Schmidt condensation is...
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

