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

Abstract

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 (BF(3)·Et(2)O or Al(OTf)(3)), gives 2-C-vinyl glucosides in good yields and α-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.