Intramolecular reactions of compounds derived from sugars. Part III. High diastereoselection in the intramolecular diels-alder reaction of sugar based 1,7(E,Z),9-decatrienes
olefination reactions. When or were subjected to intramolecular Diels-Alder reaction under thermal conditions the same, cis-fused octahydronaphtalene enantiomer was formed exclusively. This phenomenon can be explained by Z→E isomerization of to . Similaryly, when a mixture of trienones and was heated at 160° the formation of a single product was observed. Stereochemical outcome of the reactions can be rationalized