Extending the scope of the Ferrier reaction: fragmentation-rearrangement reactions of selectively substituted 1,2-cyclopropanated glucose derivatives

Two further variations of the Ferrier-type allylic rearrangements of 1,2-cyclopropanated glucose derivatives bearing an acetoxylated carbon at the 1'-position are described. In the first, treatment of the cyclopropanated sugar with a nucleophile (ROH, PhSH, azide) and Lewis acid (BF3 center dot Et2O or Al(OTf)(3)), gives 2-C-vinyl glucosides in good yields and alpha-selectivities. Alternatively, treatment with a combination of Lewis acid and acetic acid leads to a novel fragmentation-rearrangement to form a 2,3-dehydro-2-formyl-C-glycoside. [GRAPHICS] (C) 2012 Elsevier Ltd. All rights reserved.