[reaction: see text] Methyl-l-callipeltose, the carbohydrate associated with callipeltoside A, has been synthesized in eight steps and 23% overall yield from enantioenriched allylsilane 6 and acetaldehyde. The key steps are a highly diastereoselective formal [4 + 2] annulation and a Cr(VI)-catalyzed oxidative C-C bond cleavage to produce lactone 11.
Department of Chemistry and Center for Chemical Methodology and Library Development, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
