The chemical composition of Murraya paniculata. The structure of five new coumarins and one new alkaloid and the stereochemistry of murrangatin and related coumarins

The structural determination of five new coumarins: murralonginol isovalerate (1b), isomurralonginol isovalerate (2b), murrangatin isovalerate (6b), minumicrolin isovalerate (7b), chloculol (4a), and a new indole alkaloid, paniculol (18), is described.The relative configurations hitherto reported for the α-glycol moieties in murrangatin (erythro) and minumicrolin (threo) have been revised to threo for compound (6a) and erythro for compound (7a), respectively on the basis of NOE experiments performed on the acetonides (6e) and (7e). Furthermore, the absolute configuration of (–)-murrangatin (6a) has been shown to be [R,R] by analysis of the CD spectrum of tetrahydromurrangatin dibenzoate (16b). The reaction of phebalosin (8) with hydrochloric acid has also been re-examined.