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Cyclo(L\u2010Pro\u2010L\u2010Xxx) is mostly isomerized to cyclo(D\u2010Pro\u2010L\u2010Xxx) in D<jats:sub>2<\/jats:sub>O solution, whereas cyclo(D\u2010Pro\u2010L\u2010Xxx) is only slightly isomerized to cyclo(L\u2010Pro\u2010L\u2010Xxx) even under stronger basic conditions. After adding a deuterated organic solvent (CD<jats:sub>3<\/jats:sub>COCD<jats:sub>3<\/jats:sub>, CD<jats:sub>3<\/jats:sub>SOCD<jats:sub>3<\/jats:sub> or CD<jats:sub>3<\/jats:sub>OD) to a D<jats:sub>2<\/jats:sub>O solution of cyclo(L\u2010Pro\u2010L\u2010Xxx), cyclo(D\u2010Pro\u2010L\u2010Xxx), or increasing the temperature of the D<jats:sub>2<\/jats:sub>O solution, CH\u2010\u03c0 interaction between H<jats:sub>9<\/jats:sub> and the benzene ring of cyclo (D\u2010Pro\u2010L\u2010Xxx) was stronger than that between H<jats:sub>8\u03b1<\/jats:sub> and the benzene ring of cyclo(L\u2010Pro\u2010L\u2010Xxx).<\/jats:p>","DOI":"10.1002\/ansa.202100047","type":"journal-article","created":{"date-parts":[[2021,11,10]],"date-time":"2021-11-10T15:56:12Z","timestamp":1636559772000},"page":"38-46","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Analysis of the isomerization of diketopiperazine consisting of proline and aromatic 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