Copper-Catalyzed Annulation of Oxime Acetates with α-Amino Acid Ester Derivatives: Synthesis of 3-Sulfonamido/Imino 4-Pyrrolin-2-ones

Miao, Chun‐Bao; Zheng, Anqi; Zhou, Li-Jin; Lyu, Xinyu; Yang, Hai‐Tao

doi:10.1021/acs.orglett.0c00870

Cited by 33 publications

(14 citation statements)

References 66 publications

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“…Exposure of N -benzenesulfonyl benzaldimine 9a to the standard condensation conditions afforded approximately 10% of the corresponding trisubstituted-2,5-dihydroimidazole 10a , suggesting a requirement for an equivalent of BF 3 ·OEt 2 . Employing an equivalent of BF 3 ·OEt 2 allowed the efficient conversion of the imine series N -benzenesulfonyl benzaldimine ( 9a ), N -phenyl benzaldimine ( 9b ), and O -acetyl cyclohexanoneoxime ( 9c ), to the corresponding dihydroimidazoles 10a – 10c (Table , entries 1–3). The anisyl group in Asmic ( 1b ) was found not to be essential as replacement with a 2-naphthyl substituent ( 1 , Ar = 2-naphthyl) allowed analogous condensations with benzaldehyde to afford 10d and with N -benzenesulfonyl benzaldimine ( 9a ) to afford 10e (Table , entries 4 and 5, respectively).…”

Section: Resultsmentioning

confidence: 99%

Asmic Isocyanide [3 + 2] Cascade to Dihydrooxazoles and Dihydroimidazoles

et al. 2020

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The versatile isocyanide building block Asmic, anisylsulfanylmethylisocyanide, reacts with aldehydes and ketones in a BF 3 •OEt 2 -mediated condensation to afford thioimidoyl-substituted 2,5-dihydrooxazoles. The condensation is distinguished from related base and transition-metal-catalyzed [3 + 2] processes in proceeding via the condensation of aldehydes and ketones with 2 equiv of an isocyanide followed by a molecular rearrangement that installs four new bonds. BF 3 •OEt 2 mediates an analogous condensation of Asmic with imines to generate N-substituted dihydroimidazoles. Mechanistically, BF 3 • OEt 2 activates the isocyanide to facilitate deprotonation evolving to a zwitterion that traps π-electrophiles in a formal [3 + 2] process. A second deprotonation−condensation with Asmic initiates a structural rearrangement involving a sulfanyl elimination− addition transposition sequence. The resulting dihydrooxazoles and dihydroimidazoles contain a thioimidate that serves as a diversification point for further elaboration.

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Section: Resultsmentioning

confidence: 99%

Asmic Isocyanide [3 + 2] Cascade to Dihydrooxazoles and Dihydroimidazoles

et al. 2020

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“…[76] Some studies, however, showed that 1,3-HAT is possible in the presence of certain catalysts. [95][96][97][98][99][100][101][102][103][104][105][106] It should be noted that copper catalysis was involved in most examples where 1,3-HAT was supposed to have occurred with oxime-derived iminyl radicals.…”

Section: 3-hydrogen Atom Transfermentioning

confidence: 99%

“…In the presence of copper (I) salts oxime esters 65 underwent intermolecular cyclization with sulfonamides 66 or anilines 67 with the formation of pyrrolines 68 or 69 , respectively (Scheme 26). [101] The key stages of the proposed mechanism are shown in the bottom part of Scheme 26 on the example of substrate 67 . The authors suggested that Cu II oxidizes sulfonamides 66 and anilines 67 to the corresponding imines.…”

Section: Reactions Involving Intramolecular 1n‐hydrogen Atom Transfer To Iminyl Radical Centermentioning

confidence: 99%

Oxime‐Derived Iminyl Radicals in Selective Processes of Hydrogen Atom Transfer and Addition to Carbon‐Carbon π‐Bonds

et al. 2021

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Oximes represent one of the fundamental organic compound classes with a wide range of synthetic applications. In the last decade O-substituted oximes were recognized as the synthetically available and versatile precursors of iminyl radicals via one-electron oxidation or one-electron reduction employing visible light photoredox catalysts, salts of abundant metals (such as Cu or Fe), or other convenient reagents. Iminyl radicals are powerful synthons for various processes of cyclization, ringopening, CH-functionalization, and coupling. The present review is focused on the synthetic methods based on oxime-derived iminyl radicals developed in the last few years excluding ring opening reactions of cyclic iminyl radicals that were summarized in recent publications. The review consists of two main parts:(1) reactions of iminyl radicals involving 1,n-hydrogen atom transfer (n = 5 in most cases) and (2) reactions involving the addition of iminyl radical to the carbon-carbon π-bond.

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“…In the past 10 years, O -acyl oximes as versatile intermediates were employed in chemical transformation for the synthesis of different heterocycles . The N–O bond in the oxime acetate is much more active than the normal N–O bond; there are many studies on the synthesis of nitrogen-containing heterocycles by breaking the N–O bond of O -acyl oximes, most of which are synthesized in the presence of transition metals, including Pd, Rh, Ru, Fe, Co, Cu, etc. In addition, microwave, UV, and visible light catalyses have also been reported.…”

Section: Introductionmentioning

confidence: 99%