General and Stereocontrolled Approach to the Chemical Synthesis of Naturally Occurring Cyanogenic Glucosides.

An effective method for the chemical synthesis of cyanogenic glucosides has been developed as demonstrated by the synthesis of dhurrin, taxiphyllin, prunasin, sambunigrin, heterodendrin, and epiheterodendrin. O-Trimethylsilylated cyanohydrins were prepared and subjected directly to glucosylation using a fully acetylated glucopyranosyl fluoride donor with boron trifluoride-diethyl etherate as promoter to afford a chromatographically separable epimeric mixture of the corresponding acetylated cyanogenic glucosides. The isolated epimers were deprotected using a triflic acid/MeOH/ion-exchange resin system without any epimerization of the cyanohydrin function. The method is stereocontrolled and provides an efficient approach to chemical synthesis of other naturally occurring cyanogenic glucosides including those with a more complex aglycone structure.