Conversion of lapachol to array of furano and pyranonaphthoquinone congeners

Department of Chemistry, University of Rajasthan, Jaipur-302 004, India
E-mail: pahupsingh@yahoo.co.uk
Manuscript received 13 August 2004

Chemical conversion of lapachol to α-lapachune, β-lapachone, dehydro-α-lapachone, dehydroiso-α-lapachone and dehydroiso-
β-lapachone by reaction with aqueous NaNO₂ and glacial AcOH; rhinacanthin-A, stenocarpoquinone-A, stenocarpoquinone-
B and its isomer by reaction with meta-chloroperbenzoic acid at 0º for 30 min and dehydro-α-lapachone and dehydro-β-lapachone
at 25º for 4 h respectively and di- and tribromo derivatives by reaction with Br₂ in chloroform has been reviewed. In most of these reactions prenyl chain cyelises into an Oxygen function to give a number of furano and pyranonaphthoquinone derivatives. Some of these naphthoquinones co-occur with lapachol in the same plant species.