Abstract
Cyclization reactions of lapachol (1) isolated from Heterophragma adenophyllum have been studied under microwave irradiation under different conditions using alumina (acidic, basic and neutral)/silica gel/montmorillonite (KSF and K-10) as solid support along with neat reaction using 2–3 drops of DMF giving naturally occurring dehydro-α-lapachone (2), α-lapachone (3), β-lapachone (4) depending upon the nature of support and irradiation time. A novel naphthoquinone derivative adenophyllone (5) can be synthesized from lapachol using DMF under microwaves.
Acknowledgements
Financial assistance from UGC (New Delhi) is gratefully acknowledged. We are also thankful to RSIC, CDRI, Lucknow for recording the spectra.