New Derivatives of Levoglucosan by Tandem Epoxide Allyl Alcohol Rearrangement‐Cuprate Cross‐Coupling
The alkylated allyl alcohols 6a, 7, and 8 (R = Me, Et, nBu) were formed in the reaction of the Cerný epoxide 3 with the Cyano–Gilman cuprates. The one-pot reaction was initiated by base-catalyzed epoxide allyl alcohol rearrangement to compound 5, followed by unprecedented vinyl tosylate cross-coupling with the cuprates, to form the alkylation products 6a, 7, and 8. The allyl alcohol 6a was transformed into a number of new branched 1,6-anhydro sugars in series of highly stereoselective reactions. The products are stereochemically complementary to most known Cerný epoxide derivatives and may be useful as chiral building blocks for polypropionate-derived natural products. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)