Umpolung Amide Synthesis (UmAS) provides direct access to amides from an α-bromo nitroalkane and an amine. Based on its mechanistic bifurcation after convergent C-N bond formation, depending on the absence or presence of oxygen, UmAS using substoichiometric N-iodosuccinimide (NIS) under aerobic conditions has been developed. In combination with the enantioselective preparation of α-bromo nitroalkane donors, this protocol realizes the goal of enantioselective α-amino amide and peptide synthesis based solely on catalytic methods.
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http://dx.doi.org/10.1021/ol502089v | DOI Listing |
JACS Au
November 2024
School of Chemistry, Sun Yat-sen University, Guangzhou 510006, P.R. China.
J Org Chem
November 2024
College of Science, China Agricultural University, Beijing 100193, P. R. China.
Traditional methods of the α-oxidation of amides often require preactivation or umpolung of amides. In this study, we introduce a general electrochemical approach for the direct α-C()-H alkoxylation of thiophene-containing amides. This mild and selective electrochemical method provides a modular and alternative efficient route to the highly valuable α-oxygenated thiophene-containing amide scaffolds.
View Article and Find Full Text PDFOrg Lett
July 2024
School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China.
A hypervalent iodine-mediated intermolecular α-umpolung reaction between α-aryl- or alkyl-substituted amides and benzotriazoles or purine derivatives as -centered nucleophiles has been established. The reaction involves sequential intra/intermolecular oxidative C-N couplings in a controlled manner, affording tetrasubstituted 3,3'-oxindoles in moderate to good yields. This approach efficiently addresses the challenges in constructing tetrasubstituted carbon centers via α-umpolung functionalizations of carbonyl compounds and serves as a new strategy for synthesizing biologically important 3,3'-disubstituted oxindoles.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
August 2024
Department of Chemistry, Zhejiang University, Hangzhou, 310058, China.
Although dearomative functionalizations enable the direct conversion of flat aromatics into precious three-dimensional architectures, the case for simple arenes remains largely underdeveloped owing to the high aromatic stabilization energy. We herein report a dearomative sequential addition of two nucleophiles to arene π-bonds through umpolung of chromium-arene complexes. This mode enables divergent dearomative carbonylation reactions of benzene derivatives by tolerating various nucleophiles in combination with alcohols or amines under CO-gas-free conditions, thus providing modular access to functionalized esters or amides.
View Article and Find Full Text PDFWe have developed efficient synthetic reactions using enamines and enamides carrying oxygen atom substituent on nitrogen, such as N-alkoxyenamines, N,α-dialkoxyenamines, N-alkoxyanamides, and N-(benzoyloxy)enamides. The umpolung reaction by polarity inversion at the β-position of N-alkoxyenamines afforded α-alkyl-, α-aryl-, α-alkenyl-, and α-heteroarylketones by using aluminum reagent as nucleophiles. Furthermore, one-pot umpolung α-phenylation of ketones has been also developed.
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