A new format for the Castagnoli–Cushman reaction of structurally diverse dicarboxylic acids, amines, and aldehydes in the presence of aceticanhydride as dehydrating agent is described. The reaction is distinctly amenable to parallel format: the combinatorial array of 180 reactions delivered 157 products of >85% purity without chromatographic purification (of this number, 143 compounds had >94% purity)
monomethyl ester of the respective dicarboxylicacid was involved in a reaction with imines promoted by acetic anhydride at an elevated temperature. Instead of the initially expected δ-lactam products of the Castagnoli-Cushman-type reaction, medicinally important 3-amino-2-azetidinones were obtained as the result of cyclization, involving a methylene group adjacent to an acid moiety. In contrast, replacing
1,1′-Carbonyldiimidazole as a cyclodehydrating agent for the Castagnoli–Cushman reaction of dicarboxylic acids and imines
作者:Evgeny G. Chupakhin、Olga Yu. Bakulina、Dmitry V. Dar’in、Mikhail Krasavin
DOI:10.1016/j.mencom.2019.05.016
日期:2019.5
A novel protocol for the Castagnoli-Cushman reaction of dicarboxylic acids and imines comprises the use of 1,1'-carbonyldiimidazole as the cyclodehydrating agent to in situ produce the intermediate anhydrides. In contrast to previously developed procedure involving the use of acetic anhydride, the current protocol allows one to utilize substrates prone to acylation or acid-promoted transformations, which significantly broadens the reaction scope of lactams to be obtained.