Selective Access to 4‑Substituted 2‑Aminothiazoles and 4‑Substituted 5-Thiocyano-2-aminothiazoles from Vinyl Azides and Potassium Thiocyanate Switched by Palladium and Iron Catalysts

A highly selective construction of 4-substituted 2-aminothiazoles and 4-substituted 5-thiocyano-2-aminothiazoles, respectively, catalyzed by palladium­(II) acetate and promoted by iron­(III) bromide from vinyl azides and potassium thiocyanate has been developed. Use of readily available starting materials, high selectivity, as well as mild reaction conditions make this practical method particularly attractive

One-pot three-component protocol for the synthesis of substituted 2-aminothiazoles

<p>Substituted 2-aminothiazoles have been synthesized from α-nitro-epoxides, cyanamide, and sodium sulfide through a facile, three-component, and ecofriendly protocol with good to excellent yields. This reaction was achieved at room temperature without any additives. A possible mechanism has also been proposed.</p

Palladium-Catalyzed C–H Functionalization Using Guanidine as a Directing Group: Ortho Arylation and Olefination of Arylguanidines

Palladium-catalyzed C–H functionalization using guanidine as the directing group was achieved under mild reaction conditions. Various guanidine derivatives were produced in moderate to good yields by using simple unactivated arenes or ethyl acrylate as the source of arylation or olefination, respectively

Parallel Synthesis of 1,6-Disubstituted-1,2,4-triazin-3-ones on Solid-Phase

A parallel solid-phase synthesis of 1,6-disubstituted-1,2,4-triazin-3-ones from MBHA resin is described. The reduction of resin-bound nitrosamino acids provides hydrazines efficiently without affecting the amide bond. The trityl protected hydrazine is then reduced with borane, and cyclized with 1,1-carbonyldiimidazole. The desired products are cleaved from their solid support and obtained in good yield and purity. This methodology is of value for the rapid parallel preparation of these potentially bioactive molecules

Palladium-Catalyzed H/D Exchange Reaction with 8‑Aminoquinoline as the Directing Group: Access to ortho-Selective Deuterated Aromatic Acids and β‑Selective Deuterated Aliphatic Acids

We develop a palladium-catalyzed H/D exchange reaction with 8-aminoquinoline as the directing group as well as D₂O as the source of deuterium atom and solvent. This reaction achieves selectively H/D exchange at the <i>ortho</i>-C–H of aromatic amides and the β-C–H of aliphatic amide. Ortho-deuterated aromatic acids and β-deuterated aliphatic acids are obtained by removal of the directing group. And a possible mechanism is also proposed

Tuning the Annulation Reactivity of Vinyl Azides and Carbazates: A Divergent Synthesis of Aza-pyrimidinones and Imidazoles

A divergent cascade annulation has been developed using readily available vinyl azides and carbazates with a wide range of substituents. Vinyl azides were successfully applied as bifunctional partners to prepare aza-pyrimidinones via 6-ring closure with carbazates as well as to construct polyfunctionalized imidazoles via 5-ring closure with <i>N</i>-substituted carbazates. The aza-heterocycles were obtained with high levels of chemoselectivity and excellent yields

One-Pot Three-Component Strategy for Functionalized 2‑Aminoimidazoles via Ring Opening of α‑Nitro Epoxides

Functionalized 2-aminoimidazole derivatives have been synthesized via a three-component domino reaction of α-nitroepoxides and cyanamide with a series of amines under mild conditions without the need for any additives. This reaction represents a practical process for the facile conversion of α-nitroepoxides to 2-aminoimidazoles via ring opening of epoxides

One-Pot Three-Component Approach to the Synthesis of Polyfunctional Pyrazoles

A simple, multicomponent, and straightforward reaction of vinyl azide, aldehyde, and tosylhydrazine affords the construction of 3,4,5-trisubstituted 1<i>H</i>-pyrazoles regioselectively in the presence of base with moderate to excellent yields. A range of functionality could be tolerated in this methodology, and a possible mechanism is proposed

A Novel Method for the Determination of Isokinetic Ratios and Its Application in the Synthesis of Two New Positional Scanning Libraries

A novel method for the direct evaluation of the equimolarity of the compounds contained in a mixture is presented. We applied the method toward calculating isokinetic ratios for the reaction between the amine termini of a resin bound peptide fragment and a sulfonyl chloride to produce equal molar mixtures of sulfonamides. The results of this study and the application of the method to the synthesis of two new positional scanning synthetic combinatorial libraries (PS-SCL) are discussed

A Novel Method for the Determination of Isokinetic Ratios and Its Application in the Synthesis of Two New Positional Scanning Libraries

A novel method for the direct evaluation of the equimolarity of the compounds contained in a mixture is presented. We applied the method toward calculating isokinetic ratios for the reaction between the amine termini of a resin bound peptide fragment and a sulfonyl chloride to produce equal molar mixtures of sulfonamides. The results of this study and the application of the method to the synthesis of two new positional scanning synthetic combinatorial libraries (PS-SCL) are discussed