RETRO-DIELS-ALDER REACTION IN AQUEOUS-SOLUTION - TOWARD A BETTER UNDERSTANDING OF ORGANIC-REACTIVITY IN WATER

The retro-Diels-Alder (RDA) reaction of anthracenedione 1a proceeds co nsiderably faster in aqueous solutions than in organic solvents. Addit ion of organic solvents to water retards the reaction, whereas glucose induces a modest acceleration. SDS micelles induce a considerable ret ardation, but even at high concentrations of surfactant (complete mice lle-substrate binding), the cycloreversion is not fully inhibited. Cor relation with data for solvatochromic indicators strongly suggest that the origin of the water-induced acceleration involves primarily enhan ced hydrogen bonding of water to the activated complex for the RDA rea ction of 1a. Activation parameters support this intramolecular Diels-A lder reactions provides insights into the contributions of hydrogen-bo nd and hydrophobic interactions to the aqueous accelerations of the la tter two types of reactions.