We have established a simple method for the preparation of crystalline Fischer's glucopyranosyl isocyanate 1. NMR spectroscopic analysis of 1 allowed the unambiguous determination of the stereochemistry at the anomeric position. Synthetic applications of glucopyranosyl isocyanate 1 were ex-

A novel approach to the synthesis of urea glycosides in aqueous media has been explored. Steyermark's glucopyranosyl oxazolidinone was found to be a good synthon for anchoring glucosyl moieties onto amines and thiols. The present method was successfully applied to establish a new route for the synthesis of urea-tethered neoglycoconjugates and pseudooligosaccharides in water.

An efficient total synthesis of (+)-conagenin was achieved. The right fragment of conagenin, alpha-methylserine containing a quaternary stereocenter attached to nitrogen, was synthesized using allyl cyanate-to-isocyanate rearrangement. The left fragment, 2,4-dihydroxy-3-methylpentanoic acid, has three contiguous stereogenic centers, which was efficiently constructed by enantioselective monoreduction of 2-alkyl-1,3-diketones reported by Cossy, and chelation-controlled stereoselective reduction of beta-hydroxy ketone. These two fragments were coupled through intramolecular amide bond formation with high efficiency.