The base-catalysed cyclisation of phenyl N-(2-hydroxybenzyl)-N-methylcarbamates is concerted
文献信息
Vojeslav Štěrba, Oldřich Hrabík, Jaromír Kaválek, Jaromír Mindl, Andrew Williams
The kinetics of the cyclisation in aqueous solution of phenyl-(2-hydroxybenzyl)-N-methylcarbamates to 3-methyl-3,4-dihydrobenzo[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 Brønsted equations against the pKa's of the corresponding free phenols but the system does not conform to the reactivity–selectivity hypothesis. The values of the Brønsted parameters βY and βX vary as a function of Y and X according to the equations:βX = −0.179pKaHY + 0.87βY = −0.179pKaHX + 2.30The 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.
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Organic & Biomolecular Chemistry

Organic & Biomolecular Chemistry (OBC) publishes original and high impact research and reviews in organic chemistry. We welcome research that shows new or significantly improved protocols or methodologies in total synthesis, synthetic methodology or physical and theoretical organic chemistry as well as research that shows a significant advance in the organic chemistry or molecular design aspects of chemical biology, catalysis, supramolecular and macromolecular chemistry, theoretical chemistry, mechanism-oriented physical organic chemistry, medicinal chemistry or natural products. Articles published in the journal should report new work which makes a highly-significant impact in the field. Routine and incremental work is generally not suitable for publication in the journal. More details about key areas of our scope are below. In all cases authors should include in their article clear rationale for why their research has been carried out.














