Eco-friendly and regioselective synthesis of 3-(isoxazol-5)-yl) indoles from β -ethylthio- β -indolyl-α, β -unsaturated ketones in water

Abstract

Eco-friendly and regioselective synthesis of 3-(isoxazol-5)-yl)indoles had been developed from the cyclocondensation reaction of β-ethyltho-β-indolyl-α, β-unsaturated ketones and hydroxyl -amine hydrochloride. It was found that in the presence of 1 equivalent of 4-dodecylbenzene sulfonic acid (DBSA) in boiling water, β-ethyltho-β-indolyl-α, β-unsaturated ketones efficiently reacted with hydroxylamine hydrochloride to afford 3-(isoxazol-5)-yl)indoles in good yields and with good to excellent regioselectivity. The method features the advantages of eco-friendly process, good yield and regioselevtivity, operational simplicity, broad substrate scope and ease of scale-up.