A large gem??dimethyl effect in the cyclization of ω??phenylhydantoic acids: computational modeling of the gem??dimethyl effect on the acid??or base??catalyzed …

PM Ivanov, IG Pojarlieff, IB Blagoeva…

Index: Ivanov; Pojarlieff; Blagoeva; Jaime; Angelova; Koedjikov Journal of Physical Organic Chemistry, 2004 , vol. 17, # 5 p. 423 - 430

Full Text: HTML

Citation Number: 7

Abstract

Abstract The rates of the cyclization of methyl-substituted 5-phenylhydantoic acids were measured in acid solutions. A particularly strong gem-dimethyl effect (GDME) was observed with the N-methyl compounds amounting to an acceleration of six powers of ten for the 2, 2, 3-trimethyl derivative. The variations in the free energies of activation for the cyclization of hydantoic acids and esters were modeled by the strain energies of the tetrahedral ...