No abstract

A selective monodefluorinative alkylation of 3,3-difluorooxindoles is achieved. The reaction starts by the attack of a 4-dimethylaminopyrine-boryl radical to the carbonyl oxygen atom of 3,3-difluorooxindoles, followed by a spin-center shift to generate radical intermediates with the elimination of a fluoride anion. The subsequent radical addition to alkenes affords a range of 3-alkyl-fluorooxindoles products. The strategy offers access to C-3 functionalized oxindoles with wide substrate scope and tolerates a wide range of functional groups.

Withania somnifera is endemic to Ethiopia where its leaf and root is traditionally used for the treatment of malaria in south Ethiopia. The main purpose of this study was to investigate phytochemicals and antioxidant activity of the leaf extract of Withania somnifera. The anti-oxidant potential and total antioxidant potential was determined by using reducing power determination method and phosphomolb date method respectively. As per the phytochemical tests, the methanol extract revealed that presence of tannins, phenolics, flavonoids, saponins and, alkaloids while all are absent in hexane extract. The antioxidant capacity of methanol, acetone and hexane leaf extracts of Withania somnifera were found to be 494.088±0.230, 104.190±0.020 and 3.413±0.023 mg of ascorbic acid per 10 mg of dry weight of antioxidant in the reducing power, respectively and it’s total antioxidant capacity of these extracts were 45.41±0.018, 8.70±0.004 and 0.38±0.002mg of ascorbic acid per 10 mg of dry weight of the crude extract. Thus, the results of the present investigation infer that this plant extracts possess potent antioxidant. Therefore it is strongly recommended to isolate the antioxidant components.

A boryl radical-promoted dehydroxylative alkylation of 3-hydroxy-oxindole derivatives is achieved. The reaction starts from addition of 4-dimethylamino­pyridine (DMAP)-boryl radical to the amide carbonyl oxygen atom, which induces a spin-center shift process to promote the C–O bond cleavage. The elimination of a hydroxide anion from a free hydroxy group is also accomplished. Capture of the generated carbon radical with alkenes furnishes a variety of C-3 alkylated oxindoles. This method features a simple operation and broad substrate scope.