ChemInform Abstract: Amine‐Free Approach Toward N‐Toluenesulfonyl Amidine Construction: A Phosphite‐Mediated Beckmann‐Like Coupling of Oximes and p‐Toluenesulfonyl Azide.

Fleury, Lauren M.; Wilson, Erin E.; Vogt, Monika; Fan, Tiffany J.; Oliver, Allen G.; Ashfeld, Brandon L.

doi:10.1002/chin.201414201

Cited by 4 publications

(4 citation statements)

References 16 publications

(26 reference statements)

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“…4−10 The structure itself is present in various natural products and biologically active compounds such as janoxepin, pentamidine, and sildenafil (see Figure 1). 11,12 Multiple methods exist for the synthesis of amidines in general, including the Pinner reaction, 13 substitution of phenoxyimidates, 14 Beckman-type rearrangements, 15 and dehydrogenative coupling reactions, 16,17 or by catalysis with palladium 14,18−21 or nickel, 22 as well as some multicomponent reactions. 23−33 Chang developed strategies for the synthesis of sulfonated and phosphorylated amidines via traditional click chemistry with azides, followed by a thermal N 2 exclusion, resulting in a net coupling of a nitrene to an alkyne.…”

Section: ■ Introductionmentioning

confidence: 99%

Efficient Copper-Catalyzed Multicomponent Synthesis of N-Acyl Amidines via Acyl Nitrenes

Vliet

Polak

Siegler³

et al. 2019

J. Am. Chem. Soc.

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Direct synthetic routes to amidines are desired, as they are widely present in many biologically active compounds and organometallic complexes. N-Acyl amidines in particular can be used as a starting material for the synthesis of heterocycles and have several other applications. Here, we describe a fast and practical copper-catalyzed three-component reaction of aryl acetylenes, amines, and easily accessible 1,4,2-dioxazol-5-ones to N-acyl amidines, generating CO2 as the only byproduct. Transformation of the dioxazolones on the Cu catalyst generates acyl nitrenes that rapidly insert into the copper acetylide Cu–C bond rather than undergoing an undesired Curtius rearrangement. For nonaromatic dioxazolones, [Cu(OAc)(Xantphos)] is a superior catalyst for this transformation, leading to full substrate conversion within 10 min. For the direct synthesis of N-benzoyl amidine derivatives from aromatic dioxazolones, [Cu(OAc)(Xantphos)] proved to be inactive, but moderate to good yields were obtained when using simple copper(I) iodide (CuI) as the catalyst. Mechanistic studies revealed the aerobic instability of one of the intermediates at low catalyst loadings, but the reaction could still be performed in air for most substrates when using catalyst loadings of 5 mol %. The herein reported procedure not only provides a new, practical, and direct route to N-acyl amidines but also represents a new type of C–N bond formation.

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Section: ■ Introductionmentioning

confidence: 99%

Efficient Copper-Catalyzed Multicomponent Synthesis of N-Acyl Amidines via Acyl Nitrenes

Vliet

Polak

Siegler³

et al. 2019

J. Am. Chem. Soc.

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show abstract

“…[82][83][84] Surprisingly, while most complexes perform poorly, [Cu(OAc)(Xantphos)] gave a very high selectivity. The reaction works well in a variety of different solvents under aerobic conditions at room temperature (Table 1, entries [12][13][14][15][16][17][18][19]. Results obtained in toluene and ethyl acetate show that the reaction is selective in both polar and apolar solvents.…”

Section: Resultsmentioning

confidence: 99%

“…[4][5][6][7][8][9][10] The structure itself is present in various natural products and biologically active compounds such as Janoxapin, Pentamidine and Sildenafil (see Figure 1). 11,12 Multiple methods exist for the synthesis of amidines in general, including the Pinner reaction, 13 substitution of phenoxyimidates, 14 Beckman-type rearrangements, 15 dehydrogenative coupling reactions, 16,17 or by catalysis with palladium 14,[18][19][20][21] or nickel, 22 as well as some multi-component reactions. [23][24][25][26][27][28][29][30][31][32][33] Chang developed strategies for the synthesis of sulfonated and phosphorylated amidines via traditional click chemistry with azides, followed by a thermal N2 exclusion, resulting in a net coupling of a nitrene to an alkyne.…”

Section: Introductionmentioning

confidence: 99%

Efficient Copper Catalyzed Multi-component Synthesis of N-acyl amidines via Acyl Nitrenes

Vliet¹,

Polak²,

Siegler³

et al. 2019

Preprint

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Direct synthetic routes to amidines are desired, as they are widely present in many biologically active compounds and organometallic complexes. N-Acyl amidines in particular can be used as a starting material for the synthesis of heterocycles and have several other applications. Here, we describe a fast and practical copper catalyzed 3-component reaction of aryl acetylenes, amines and easily accessible 1,4,2-dioxazol-5-ones to N-acyl amidines, generating CO<sub>2</sub> as the only by-product. Transformation of the dioxazolones on the Cu-catalyst generates acyl nitrenes that rapidly insert into the copper acetylide Cu-C bond rather than undergoing an undesired Curtius rearrangement. For non-aromatic dioxazolones, [Cu(OAc)(Xantphos)] is a superior catalyst for this transformation, leading to full substrate conversion within 10 minutes. For the direct synthesis of N-benzoyl amidine derivatives from aromatic dioxazolones, [Cu(OAc)(Xantphos)] proved to be inactive, but moderate to good yields were obtained when using simple CuI as the catalyst. Mechanistic studies revealed the aerobic instability of one of the intermediates at low catalyst loadings, but the reaction could still be performed in air for most substrates when using catalyst loadings of 5 mol%. The herein reported procedure does not only provide a new, practical and direct route to N-acyl amidines, but also represents a new type of<br>C-N bond formation.

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“…Thus, a green transition-metal-free protocol with readily available reagents for the synthesis of diverse amidines in a domino fashion would be of great interest. 11,15 Herein we report a mild, transition-metal-free three-component reaction for N-acyl amidine synthesis from trans-β-nitrostyrene derivatives, tert-butyl dibromocarbamate (BocNBr 2 ), and amines (Scheme 1e).…”

Section: ■ Introductionmentioning

confidence: 99%

A Metal-Free Three-Component Reaction of trans-β-Nitrostyrene Derivatives, Dibromo Amides, and Amines Leading to Functionalized Amidines

et al. 2018

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A mild, metal-free, and multicomponent route for the preparation of N-acyl amidines from nitroalkene derivatives, dibromo amides, and amines has been developed that accesses an initial α,α-dibromonitroalkane intermediate that can undergo C–C bond cleavage. This protocol offers an alternative approach toward N-acyl amidines and features the rapid construction of amidine frameworks with high diversity and complexity. The procedure also accesses bisamidine and α,β-unsaturated amidines which are challenging targets by traditional methods.

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ChemInform Abstract: Amine‐Free Approach Toward N‐Toluenesulfonyl Amidine Construction: A Phosphite‐Mediated Beckmann‐Like Coupling of Oximes and p‐Toluenesulfonyl Azide.

Abstract: The reaction of oximes (I) with the chlorophosphite (II) and tosyl azide is examined resulting in the formation of N‐tosyl amidines through a Beckmann‐type process.

Cited by 4 publications

References 16 publications

Efficient Copper-Catalyzed Multicomponent Synthesis of N-Acyl Amidines via Acyl Nitrenes

Efficient Copper-Catalyzed Multicomponent Synthesis of N-Acyl Amidines via Acyl Nitrenes

Efficient Copper Catalyzed Multi-component Synthesis of N-acyl amidines via Acyl Nitrenes

A Metal-Free Three-Component Reaction of trans-β-Nitrostyrene Derivatives, Dibromo Amides, and Amines Leading to Functionalized Amidines

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