Chiral building blocks from d-xylose and their application in synthesis of avocadotriol monoacetate

Facile routes to several enantiomerically pure flexible chiral building blocks carrying a hidden syn or anti 1,3-diol motif were developed with the inexpensive and readily available carbohydrate d-xylose as the starting material. Application of the newly developed chiral building blocks in total synthesis is exemplified through a synthesis of (2S,4S)- and (2S,4R)-avocadotriol. Both triols were selectively acetylated on the primary hydroxyl group in high yields with Novozyme 435/vinyl acetate. On the basis of comparison of the 1H NMR, optical rotation, and melting point data, the natural avocadotriol 1-monoacetate was assigned to be of (2R,4R) configuration.