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Indexed by:期刊论文

Date of Publication:2016-11-21

Journal:CHEMISTRY-A EUROPEAN JOURNAL

Included Journals:SCIE、EI、PubMed

Volume:22

Issue:48

Page Number:17156-17159

ISSN No.:0947-6539

Key Words:amino acids; carbon dioxide fixation; carboxylation; transition-metal-free synthesis; umpolung

Abstract:A straightforward and transition-metal-free approach for the efficient synthesis of -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.