Coumarins and dihydrocinnamic acid derivatives from Micromelum falcatum

Besides the known coumarins microminutinin and 6-methoxymicrominutinin, the new dihydrocinnamic acid derivatives 3,4-dihydro-1,2-secomicrominutinin, 3 ,4-dihydro-1,2-secomicrominutinin methylester and 3,4-dihydro-1,2-secomicro minutinin-9-O-glucoside as well as the new 8-prenylated coumarin microfalca tin isovalerate were isolated from the leaves of Micromelum falcatum (Rutac eae). The structures were elucidated by mass and NMR spectroscopy. The rela tive configuration of microfalcatin isovalerate was established as 1',2'-th reo by analysis of the NOE effects of its acetonide. (C) 1999 Elsevier Scie nce Ltd. All rights reserved.