BIOGENESIS-LIKE TRANSFORMATION OF SALIDROSIDE TO RENGYOL AND ITS RELATED CYCLOHEXYLETANOIDS OF FORSYTHIA SUSPENSA

Article abstract of DOI:10.1016/S0040-4020(01)89229-2

Photooxygenation of salidroside (8) in methanol in presence of Rose Bengal afforded cornoside (9), which, on high pressure hydrogenation with 5percent palladium on activated carbon, yielded rengyoside B (6).Reduction of 6 with sodium borohydride gave rengyoside A(5) stereoselectively.By enzymatic hydrolysis, 9, 6 and 5 furnished rengyolone (4), rengyoxide (3) and rengyol (1), respectively. Similerly, p-hydroxyphenylethanol (10), the aglycone part of salidroside (8), was oxygenated photochemically to a dienone alcohol, which cyclized spontaneously to rengyolone (4).Hallerone (17) was obtained by the photooxygenation of p-hydroxyphenylethyl acetate (10b).Thus the plausible biosynthetic routes from salidroside (8) to rengyol (1) and the related natural cyclohexylethanoids were simulated chemically.