75866-89-6Relevant academic research and scientific papers
Stereoelectronic control in acetal formation
Beaulieu, Normand,Dickinson, Robert A.,Deslongchamps, Pierre
, p. 2531 - 2536 (2007/10/02)
The cyclization under acidic conditions of bicyclic and monocyclic hydroxypropyl methoxytetrahydropyrans 1 and 4 is reported.At room temperature, compound 1 gives only cis tricyclic acetal 2.At reflux, compound 2 equilibrates to yield a mixture of cis and trans tricyclic acetals 2 (45percent) and 3 (55percent).Compound 4 gives directly the equilibrium mixture of cis and trans bicyclic acetals 5 (55percent) and 6 (45percent) at room temperature.The specific formation of 2 from 1 constitutes strong experimental evidence that acetal formation is controlled by stereoelectronic effects.The anomeric effect can be estimated (ca. 1.5 kcal/mol) from the equilibrium study of 2 and 3.This value confirms the result previously obtained by Descotes (9).
