Ethyl acetate 4-hydroxybenzaldehyde

Keywords hydroxybenzaldehyde, ethyl acetate, Knoevenagel condensation, microwave irradiation, coumarin... 

The activity of the ethanolic extract of both the pods and the seeds of M. oleifera is equivalent at the dose of 30 mg/kg. The ethyl acetate phase of the ethanolic extract of pods has more hypotensive potency at the same dose. The bioassay-directed fractionation ethyl acetate phase of the ethanohc extract of pods led to the isolation of thiocaibamate and isothiocyanate glycosides which are also the hypotensive compounds observed in M. oleifera leaves. Two new compounds, 0-[2 -hydroxy-3 -(2 heptei5rloxy)]-propyl undecanoate and O-ethyl-4-[(a-Z-rhamnosyloxy)-benzyl] carbamate along with methyl p-hydroxybenzoate and p-sitosterol are also isolated from the pods. The latter two compounds and /7-hydroxybenzaldehyde shows promising hypotensive activity (89). 

To a magnetically stirred solution of 2-hydroxybenzaldehyde (1, 1 mmol) and Meldrum s acid (2, 1 mmol) in ethanol or methanol (5 mL) (and alcohol 4 other than ethanol or methanol in dichloromethane) was added isocyanide (3,1 mmol) and the reaction mixture was stirred at room temperature for stipulated period (5-8 h in ethanol or methanol and 24-36 h in dichloromethane). After completion of the reaction, as indicated by TLC (ethyl acetate/n-hexane, 2 1), the precipitate (in case of dichloromethane medium, the solvent was removed under vacuum to have the crude mass) was washed with ethanol or diethyl ether to afford substituted 3,4-dihydrocoumarin 5 as white powder in good to excellent yield (70-96%). Each of the products was characterized by analytical as well as detailed spectral studies including IR, NMR, NMR, and mass. 

Di-f-butyl-4-hydroxybenzaldehyde (0.411 mol) and 300 ml acetic anhydride were mixed, then treated with 0.6 ml 70% perchloric acid, and stirred overnight at ambient temperature. The solution was then cooled in an ice bath and treated with the portionwise addition of 2000 ml ice water. An oil was formed, which solidified into brown lumps, and was washed with water and acetic acid, then dried under vacuum. The solid was boiled 10 minutes with 250ml ethyl alcohol containing 25ml 12M HC1, then cooled, and resolidified by pouring into 2000 ml water. The solid was washed with 1000 ml water and the product isolated in 99.4% yield as a light brown solid, mp = 65.2-74.5°C... 

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