Isolation and structure of two new dihydroisocoumarins from Kigelia pinnata

Synthesis of (±)-kigelin

“…mp 176-180 °C; R f =0.13 (pet. ether-ethyl acetate 6:4); IR (KBr) ν max /cm -1 : 3194, 1730, 1594, 1695, 1244, 1047 C, 58.20; H, 6.01; Found: C, 58.14;3, Keto acid (5) (0.634 mmol, 0.17 g) was heated under reflux with sodium borohydride (0.15 g) in absolute ethanol (15.2 mL) for 4 h. Ethanol was then rotary evaporated, the residue diluted with cold water and acidified with diluted sulfuric acid to give a precipitate, which was extracted with ethyl acetate. Finally the solvent was rotary evaporated to afford 6 as a semi solid (0.13 g, 0.475 mmol, 75%).…”

“…Govindachari et al isolated kigelin 3 as the major constituent of plant from the root heartwood of Kigelia pinnata DC. The structure of kigelin was established by chemical methods and spectroscopic techniques as 8-hydroxy-6,7-dimethoxy-3-methyl-3,4-dihydroisocoumarin (1) and it was concluded that the absolute configuration at C-3 was R on the basis of CD spectral analysis ( Figure 1).…”

“…[8][9][10][11][12][13][14] The aim of present study was to devise an efficient synthesis of commercially important and bioactive dihydroisocoumarin 1. The requisite acid 4 was prepared in two steps in good yield from the commercially available 3-(3,4,5-trimethoxyphenyl)propionic acid (2) using the method of Bauta et al 15 Thus, cyclodehydration of 2 using polyphosphoric acid gave 5,6,7-trimethoxy-1-indanone (3). A toluene solution of indanone 3 and diethyl oxalate was treated with a suspension of sodium methoxide in toluene followed by the addition of potassium hydroxide and 30% H 2 O 2 to furnish 4 (Scheme1).…”

“…7 The great biological and commercial importance of kigelin together with its simple structure has made kigelin an attractive target for synthesis. [8][9][10][11][12][13][14] The aim of present study was to devise an efficient synthesis of commercially important and bioactive dihydroisocoumarin 1. …”

Isolation and in vitro antiamoebic activity of iridoids isolated from Kigelia pinnata

“…23 Govindachari and his colleages isolated kiglin and 6-methoxymellein together with two known compounds, stigmasterol and lapachol from the roots of this plant. 24 They also isolated kigelin, β-sitosterol, 3-dimethylkigelin and ferulic acid from its bark. 25 Dorothy et al isolated five minor constituents from root bark of K.…”