Three new coumarins and a new coumarin glycoside from Micromelum integerrimum

Three new coumarins, integmarins A-C (1-3), and a new coumarin glycoside, integmaside A (4) were isolated from the leaves and stems of Micromelum integerrimum. Their structures were elucidated on the basis of 1D and 2D NMR and MS data, and their absolute configurations were assigned according to the ECD data of the in situ formed transition metal complexes and comparison of experimental and calculated ECD data. Compounds 1 and 2 are two rare coumarins with butyl and propyl moieties at the C-6 position; compound 3 is a novel coumarin with a highly oxidized prenyl group, and compound 4 is a rare bisdihydrofuranocoumarin glycoside.