309965-32-0Relevant academic research and scientific papers
The base-catalysed cyclisation of phenyl N-(2-hydroxybenzyl)-N-methylcarbamates is concerted
Sterba, Vojeslav,Hrabik, Oldrich,Kavalek, Jaromir,Mindl, Jaromir,Williams, Andrew
, p. 415 - 421 (2003)
The kinetics of the cyclisation in aqueous solution of phenyl-(2-hydroxybenzyl) -N-methylcarbamates to 3-methyl-3,4-dihydrobenzol[e][1,3]oxazin-2-ones and phenolate ions fit the rate law: kobs = kc/(1 + [H3O+]/ ka) The values of kc and pKa fit Broonsted equations agains the pKa's of the corresponding free phenols but the system does not conform to the reactivity-selectiviy hypothesis. The values of the Broonsted parameters βY and βX vary as a function of Y and X according to the equations: βX = -0.179pKaHY + 0.87 βY = -0.179pKaHX + 2.30 The magnitude and sign of the Cordes-Thornton cross-interaction coefficient pXY(-0.179) rule out a stepwise mechanism involving a tetrahedral intermediate and is consistent with a concerted displacement mechanism. A similar concerted mechanism is proposed for the base-catalysed cyclisation of phenyl-N-(2-hydroxyphenyl)-N-methylcarbamate esters to benzoxazol-2-ones.
