Search

Abstract A method for the catalytic hydrophosphinylation of internal ynamides with H -phosphinates has been developed for the first time. The protocol employing the catalyst generated from NiBr 2 and PPh 3 could be applied to several types of ynamides and H -phosphinates, affording (E)-β-aminovinylphosphinates in a highly regio- and stereoselective manner. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract Copper acetylides are readily available and especially convenient reagents for the alkynylation of a broad range of heteronucleophiles. Upon simple activation with molecular oxygen in the presence of suitable ligands and solvents, they readily transfer their alkyne moiety at room temperature, notably yielding a variety of nitrogen- and phosphorus-substituted alkynes. We report in this manuscript an extensive study of the chemoselectivity of this alkynylation based on quantitative 13C NMR analyses. With suitable ligand/solvent combinations, various phosphorus-based nucleophiles can be alkynylated with excellent levels of selectivity, even in the presence of a large excess of a nitrogen-nucleophile. This chemoselective alkynylation could be further extended to an even more challenging selective alkynylation of a nitrogen-nucleophile over another one, further highlighting the synthetic potential of copper acetylides as alkynylating agents that can selectively "fish" a nucleophile without affecting others. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

A novel and highly efficient heterogeneous gold(I)-catalyzed [2 + 2 + 2] annulation between ynamides and nitriles has been developed that proceeds smoothly under mild conditions and provides a general and powerful tool for the preparation of a variety of tetrasubstituted pyrimidines with high atom-economy, good to excellent yield, and recyclability of the gold(I) catalyst. The reaction is the first example of the heterogeneous gold(I)-catalyzed construction of pyrimidines. [ABSTRACT FROM AUTHOR]

The iron(II) chloride- and copper(I) iodide-mediated carbozincation of a panel of substituted ynamides is described in this article. The reaction is totally regio- and stereoselective. Experiments showed that the reaction mediated with Fe(II) was more substrate dependent than the reaction performed with Cu(I). Interestingly, in the presence of allylbromide, stereoselective carboallylation can be achieved for the first time in a one-pot procedure, leading to skipped dienamides. [ABSTRACT FROM AUTHOR]

A new TfOH-mediated reaction of ynamides with nitriles as nucleophiles has been developed. The reaction works efficiently under mild reaction conditions to afford a new class of α-acylaminoenamides readily via the intermediacy of keteniminium ion. The reaction displays generality and a broad substrates scope. Additionally, the α-acylaminoenamides could be transformed to highly substituted pyridine, 4-aminopyrimidine or isoquinoline cores. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed highly regioselective synthesis of benzotriazole appended benzosultams by the tandem-cyclization of functionalized ynamides with benzotriazoles has been accomplished. This transformation involves the formation of both C N and C C bonds in a single step. Donor solvents appear to enhance the yields of the products. The methodology is also applicable for the generation of triazole/tetrazole appended benzosultams. [ABSTRACT FROM AUTHOR]

A method for Cu(OAc) 2 -catalyzed hydrophosphinylation of ynamides was developed and applied to several types of terminal ynamides and H -phosphinates. The products were transformed into β-aminophosphinates, which are useful for the preparation of biologically active compounds. [ABSTRACT FROM AUTHOR]

Abstract: Transition metal-free double oxidation of triple bonds in ynamides for synthesis of α-keto-imides is described. The successful key was combination of NIS and DMSO under atmospheric air in CPME solvent, and the reaction quickly proceeds at 0 °C within 1 h. Although the yields and substrate generality are moderate, yet the prototype protocol avoids the use of expensive, moisture-sensitive, toxic, and explosive additives, which make it potentially and significantly greener than current alternatives. [Copyright &y& Elsevier]

Abstract: A rhodium(I)-xylyl-BINAP catalyzed asymmetric [2+2+2] cycloaddition of achiral conjugated aryl ynamides with various diynes is described here. This asymmetric cycloaddition provides a series of structurally interesting chiral N,O-biaryls with excellent enantioselectivity along with a modest diastereoselectivity with respect to both C–C and C–N axial chirality. [Copyright &y& Elsevier]

Abstract: A highly stereoselective Saucy–Marbet rearrangement using chiral ynamides and propargyl alcohols is described here. This rearrangement can be catalyzed by para-nitrobenzenesulfonic acid and leads to high diastereoselectivities for a range of different chiral propargyl alcohols and ynamides in a stereochemically intriguing matched, mismatched or indifferent manner. The stereoselective Saucy–Marbet rearrangement of ynamides provides an excellent entry to highly substituted chiral homo allenyl alcohols. [Copyright &y& Elsevier]

Abstract: Substituted 3-(arylmethylene)isoindolin-1-ones can be efficiently synthesized from various ynamides and boronic acids by palladium-catalyzed Heck–Suzuki–Miyaura domino reactions. This methodology has been applied to the total synthesis of lennoxamine and a concise route to this isoindolobenzazepine alkaloid was achieved in eight steps from 2,3-dimethoxybenzoic acid via a key intermediate ynamide. [Copyright &y& Elsevier]

Abstract: A highly regio- and stereoselective Brønsted acid-catalyzed coupling of ynamides and aromatic heterocycles, such as pyrroles, furans, and indoles is described. This process is the equivalent of hydroarylation of ynamides, and leads to the efficient syntheses of an array of vinylheterocycles. Diels–Alder reaction between the vinylindoles and DMAD afforded carbazole derivatives in good yields. [Copyright &y& Elsevier]

Abstract: Ynamides react with ketenes in [2+2] cycloadditions leading to a variety of substituted 3-aminocyclobut-2-en-1-ones. The ynamides employed in these reactions are readily available via the copper-promoted N-alkynylation of carbamates and sulfonamides with alkynyl bromides and iodides. The scope of the [2+2] cycloaddition with regard to both the ketene and ynamide component is described. [Copyright &y& Elsevier]

Abstract: N-Formyl-tosylamides can be efficiently converted to N-ethynyl-tosylamides in two steps via the corresponding dichlorovinylamides. [Copyright &y& Elsevier]

Abstract: Ynamides are tested as new partners in radical and organometallic transformations. A radical cascade involving a 5-exo-dig cyclization followed by a 6-endo-trig radical trapping transforms ynamides into hetero-polycyclic compounds such as isoindoles, isoindolinones and pyrido-isoindolones. Various ene–tosylynamides react with platinum(II) chloride and lead to bicyclic nitrogenated heterocycles. This unprecedented and easily operated process can be coupled with a hydrolysis of the intermediate cyclic tosylenamides in a one-pot transformation, which provides cyclobutanones. [Copyright &y& Elsevier]

Abstract: N,N′-aryl- and N,N′-alkyl-buta-1,3-diyne-1,4-ditosylamides have been synthesized for the first time, in good to excellent yields, by copper-catalyzed dimerization of the corresponding N-aryl or N-alkyl tosylynamides. Negishi coupling of N-ethynylzinc tosylamides derivatives with (hetero)aryl iodides in the presence of Pd2dba3 and triphenylphosphine affords N-aryl and N-alkyl arylynamides in yields of up to 90%. Intramolecular [4+2] cycloaddition reactions of N-ethynylphenyl ynamides and arylynamides allow the synthesis of carbazoles and benzannulated and heteroannulated carbazoles in moderate-to-good yields. [Copyright &y& Elsevier]

Abstract: A series of diversely 1-substituted 4-amino 1,2,3-triazoles were synthesized by [3+2] cycloaddition between azides and ynamides. This copper catalyzed process represents the first examples of a ‘click reaction’ employing ynamides and should expand the scope of the ynamide chemistry both synthetically and industrially. Various azides (even highly functionalized) were allowed to react with N-benzyl, N-tosyl ynamide to give the corresponding triazole adducts in high yield and with very high levels of regioselectivity. [Copyright &y& Elsevier]

A simple and convenient synthesis of α-bisdeuterated imides is reported, hinging on the transient formation of keteniminium ions by treatment of ynamides with TfOD, followed by trapping with D 2 O. The products are obtained in good yields and with a high degree of deuterium incorporation. Gram-scale reaction and further derivatization without deuterium erosion highlight the synthetic utility of this method for the formation of a wide range of isotopically labelled compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

The [2,3]-sigmatropic rearrangement of sulfonium ylides bearing substituted allyl groups creates two contiguous stereocentres. Low diastereoselectivity is typically observed from commonly used α-diazocarboxylic ester precursors. High diastereoselectivity was previously revealed in a gold-catalyzed multicomponent route into allyl sulfonium ylides by reaction of ynamide, oxidant and allyl sulfides. The effect of substrate modifications on the diastereoselectivity have been studied, with N -phenyl methanesulfonamide derived ynamides proving the most effective. This report includes an enhanced experimental procedure, and a demonstration that the gold-catalyzed process remains highly effective at −78 °C. Image 1 [ABSTRACT FROM AUTHOR]

An efficient approach to access functionalized 3-alkenylindoles has been developed through Er(OTf) 3 -catalyzed addition of ynamides and indoles. A number of C-aryl substituted ynamides 7a-7k could react with indoles 6a-6s , affording the desired products 8aa-8sa, 8 ab-8ak, 8bd, 8bk and 8tc in moderate to excellent yields with high regioselectivities. Image 1 • An efficient approach to access functionalized 3-alkenylindoles. • Er(OTf) 3 -catalyzed addition of ynamides and indoles. • A variety of C-aryl substituted ynamides were successfully introduced to indoles. [ABSTRACT FROM AUTHOR]

A novel method for the synthesis of α -amino alkenyl-substituted hydrazone derivatives was disclosed through silver-catalyzed reaction of sulfonyl hydrazones with ynamides. The present method features mild conditions, high stereoselectivity and good yields. The proposed mechanism involves silver-mediated generation of a keteniminium ion intermediate to facilitate the stereoselective addition of hydrazones in the presence of K 2 CO 3 , while pyrazole ring could not be constructed under the current conditions. Image 1 • Synthesis of α -amino alkenyl-substituted hydrazone derivatives was achieved in high efficiency. • The reaction could proceed in a highly stereoselective manner. • This work achieved the alkenylation of NH of hydrazones that was often ignored. [ABSTRACT FROM AUTHOR]