{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,17]],"date-time":"2026-06-17T15:52:20Z","timestamp":1781711540707,"version":"3.54.5"},"reference-count":46,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2008,1,16]],"date-time":"2008-01-16T00:00:00Z","timestamp":1200441600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Inspired by the concept of ionic liquids (ILs), this study modified the original Mukaiyama\u2019s reagent, 2-chloro-1-methylpyridinium iodide (m.p. 200-dec), from ionic solid into liquids by changing its anion. The esterification of N-acetyl-L-phenylalanine was investigated as a model reaction. The microwave irradiation was more effective in esterifying N-acetyl-L-phenylalanine than the conventional reflux method. The original Mukaiyama\u2019s reagent was modified into ILs through manipulating its anion. However, only non-nucleophilic anions (such as EtSO4- and Tf2N-) were favorable since nucleophilic ones (such as CF3COO- and CH3COO-) could exchange with chlorine resulting in non-reactive coupling reagents. Two modified Mukaiyama\u2019s compounds (i.e. hydrophilic [2- ClMePy][EtSO4] and hydrophobic [2-ClMePy][Tf2N]) have been identified as the best ILtype coupling reagents. The esterification reaction was greatly enhanced by using 1- methylimidazole as the base instead of conventional toxic tertiary amines, and by using excess amount of alcohols as solvents instead of dichloromethane. Overall, the method reported is effective and \u2018greener\u2019.<\/jats:p>","DOI":"10.3390\/ijms9010033","type":"journal-article","created":{"date-parts":[[2008,12,1]],"date-time":"2008-12-01T09:42:49Z","timestamp":1228124569000},"page":"33-44","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Microwave-Assisted Esterification of N-Acetyl-L-Phenylalanine Using Modified Mukaiyama\u2019s Reagents: A New Approach Involving Ionic Liquids"],"prefix":"10.3390","volume":"9","author":[{"given":"Hua","family":"Zhao","sequence":"first","affiliation":[{"name":"Chemistry Program, Savannah State University, Savannah, GA 31404, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiyan","family":"Song","sequence":"additional","affiliation":[{"name":"Chemistry Program, Savannah State University, Savannah, GA 31404, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Janet V.","family":"Cowins","sequence":"additional","affiliation":[{"name":"Chemistry Program, Savannah State University, Savannah, GA 31404, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Olarongbe","family":"Olubajo","sequence":"additional","affiliation":[{"name":"Chemistry Program, Savannah State University, Savannah, GA 31404, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2008,1,16]]},"reference":[{"key":"ref_1","unstructured":"Bodanszky, M, Klausner, YS, and Ondetti, MA (1976). 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