New Syntheses of Demethylsuberosin, Xanthyletin, (±)-Decursinol, (+)-Marmesin, (−)-Nodakenetin, (±)-Decursin, and (±)-Prantschimgin

The title compounds, natural coumarins or their racemic modifications, were synthesized via malonic acid condensations with appropriate salicylaldehydes. Oxidation of 2,4-dihydroxy-5-(3-methyl-2 butenyl)benzaldehyde with DDQ, peracid, and acid–peracid gave the aldehydes for xanthyletin, marmesin, and decursinol, respectively. Some ¹⁴C-labelled coumarins were prepared similarly. The n.m.r. spectral data for the products are presented.