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.

Graphical Abstract

Keywords:

• Aqueous synthesis
• β-ethylthio-β-indolyl-α
• hydroxylamine hydro-chloride
• 3-isoxazolindoles
• regioselectivity
• β-unsaturatedketones

Additional information

Funding

We are grateful to the Foundation of Jilin Province Department of Education, China [JJKH20200001KJ] and the Natural Science Foundation of Jilin Province, China [20210021].