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Upon crystallization from ether\/hexane, the oxazolidine form is typically obtained as the predominant species, and the pure imine form has not been isolated to date. In this study, diphenylmethylene serine methyl ester was synthesized from serine methyl ester and benzophenone imine, purified by chromatography, and subsequently recrystallized from methanol to selectively afford the imine form in high purity. The structure was confirmed by nuclear magnetic resonance spectroscopy and single-crystal X-ray diffraction analysis. Tautomeric interconversion was investigated in deuterated chloroform at various temperatures, revealing a gradual conversion of the imine into the oxazolidine form until equilibrium was established. These findings clarify the tautomeric behavior of this compound and provide an effective strategy for the selective isolation of tautomers of serine derivatives.<\/jats:p>","DOI":"10.1093\/bbb\/zbag068","type":"journal-article","created":{"date-parts":[[2026,5,9]],"date-time":"2026-05-09T11:40:10Z","timestamp":1778326810000},"page":"992-1000","source":"Crossref","is-referenced-by-count":0,"title":["Recrystallization-induced tautomerism and selective imine formation of\n                    <i>N<\/i>\n                    -diphenylmethylene-serine methyl ester"],"prefix":"10.1093","volume":"90","author":[{"given":"Resky","family":"Nugraha","sequence":"first","affiliation":[{"name":"Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University , Sapporo, Hokkaido ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fumiya","family":"Nakayama","sequence":"additional","affiliation":[{"name":"Division of Applied Bioscience, Graduate School 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,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuki","family":"Fukuda","sequence":"additional","affiliation":[{"name":"Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University , Sapporo, Hokkaido ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zetryana Puteri","family":"Tachrim","sequence":"additional","affiliation":[{"name":"Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University , Sapporo, Hokkaido ,","place":["Japan"]},{"name":"Research Center for Pharmaceutical Ingredient and Traditional Medicine, National Research and Innovation Agency , Kawasan Sains Teknologi (KST) BJ Habibie, South Tangerang ,","place":["Indonesia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tsunayoshi","family":"Takehara","sequence":"additional","affiliation":[{"name":"The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka, Ibaraki-shi 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