Studies on the unusual stability of cis-2,5-diethoxy-2,5-bis(hydroxymethyl)-1,4-dioxane

Almost equal amounts of the trans and cis isomers of 2,5-diethoxy-2,5-bis(h ydroxymethyl)-1,4-dioxane (2trans and 2cis) are obtained by treating dihydr oxyacetone with acidic ethanol. To explain the formation of an unusually la rge quantity of 2cis, conformation analyses and equilibration experiments w ere performed for the related compounds. The results indicate that the stab ility of 2cis derives not from the hydroxymethyl groups but from the unusua lly stable twist-boat conformation. The factors stabilizing the twist-boat conformation in 2cis were discussed. (C) 1999 Elsevier Science Ltd. All rig hts reserved.