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Access to α‐Arylglycines by Umpolung Carboxylation of Aromatic Imines with Carbon Dioxide
Author(s) -
Guo ChunXiao,
Zhang WenZhen,
Zhou Hui,
Zhang Ning,
Lu XiaoBing
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201604623
Subject(s) - umpolung , carboxylation , chemistry , carbon dioxide , protonation , isomerization , potassium , solubility , organic chemistry , catalysis , ion , nucleophile
A straightforward and transition‐metal‐free approach for the efficient synthesis of α‐arylglycine derivatives from aromatic imines and carbon dioxide was enabled by an umpolung carboxylation reaction. Various substituted diphenylmethimines underwent the carboxylation smoothly with carbon dioxide in the presence of potassium tert ‐butoxide and 18‐crown‐6 to give the corresponding carboxylated products in good to high yields. Besides the enhancement of the solubility of potassium tert ‐butoxide in THF, 18‐crown‐6 also plays key roles in suppressing the reverse protonation or 1, 3‐proton shift isomerization as well as by stabilizing the carboxylated intermediate.