Radermachol and naphthoquinone derivatives from Tecomella undulata: Complete ¹H and ¹³C NMR assignments of radermachol with the aid of computational ¹³C shift prediction

Abstract

1865-1870Petroleum ether extract of the heartwood of Tecomella undulata affords radermachol, an unusual rare pigment and 2-isopropenylnaphtho[2,3-b]furan-4,9-quinone along with lapachol, tecomaquinone-I, dehydro-α-lapachone, α-lapachone, β-lapachone, cluytyl ferulate, stigmasterol and β-sitosterol. Radermachol and 2-isopropenylnaphtho [2,3-b]furan-4,9-quinone are being reported for the first time from genus Tecomella. Complete assignments of ¹H and ¹³C NMR signals of polyketide, radermachol 1, have been achieved by the ¹³C NMR chemical shift prediction using ab initio MO and DFT/GIAO methods in addition to 2D-NMR techniques