Abstract
The proposed migration of hydrogen from C-5 to C-4 in the biosynthesis of the potato phytoalexins lubimin (2). rishitin (5), and 3-hydroxylubimin (6) has been studied by incorporation of [2-2H3,2-13C]acetate. Direct observation of the predicted β-shift of the C-5 signal produced by 2H at C-4 provided conclusive confirmation of the hydride (deuteride) shift. Results of some [4,4-2H2]mevalonate incorporation experiments followed by 2Hmr are also described.