Abstract The coumarin CM-c 2, from Cnidium monnieri, 7-methoxy-8-(3-hydroxy-3-methylbut- 1-enyl) coumarin, has been synthesized by palladium acetate-catalysed condensation of 7- methoxy-8-iodocoumarin with 2-methylbut-3-en-2-ol. Its stereochemistry follows from its conversion to trans-dehydroosthol. The identity of CM-c 2 and murraol has been established. Swietenocoumarin G has been prepared similarly from bergaptol.
