Wenteng Chen

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 1H-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.

Domino Approach for the Synthesis of Pyrrolo[1,2-α]pyrazine from Vinyl Azides

A domino synthesis of pyrrolo[1,2-alpha]pyrazine from 1H-2-pyrrolecarbaldehyde and readily synthesized vinyl azides was developed. This reaction proceeded under relatively mild conditions in the presence of base. Additionally, a possible mechanism for the entire sequence is proposed.

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.

Synthesis of Polysubstituted 5-Aminooxazoles from α- Diazocarbonyl Esters and α-Isocyanoacetamides

A novel and efficient reaction for the synthesis of 2-keto-5-aminooxazoles is developed. The entire sequence is realized by simply heating a xylene solution of alpha-diazocarbonyl esters and alpha-isocyanoacetamides without any promoters. A possible mechanism for the entire sequence is proposed.

A traceless approach to amide and peptide construction from thioacids and dithiocarbamate-terminal amines

A novel and traceless strategy has been devised that allows a coupling of thioacids and dithiocarbamate-terminal amines. This strategy had been assumed to be dependent on the attachment of a functional equivalent of a cysteine side chain in earlier native chemical ligation approaches. This approach enables the traceless removal of CS2 to directly generate the desired amide bond and is compatible with a range of unprotected side chains of amino acid. The ability to produce amide or peptides by a traceless removal of the auxiliary is a significant virtue of the method. Meanwhile, the application of this new peptide-bond-forming reaction to the synthesis of novel endomorphin (EM) derivatives with various binding potencies was realized.

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.

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 N-substituted carbazates. The aza-heterocycles were obtained with high levels of chemoselectivity and excellent yields.

KI-mediated radical multi-functionalization of vinyl azides: a one-pot and efficient approach to β-keto sulfones and α-halo-β-keto sulfones

Transition metal-free oxidative coupling of vinyl azides with sulfonyl hydrazines is described. This radical process realized oxidative multi-functionalization of vinyl azides in the presence of potassium iodide and t-butyl hydroperoxide, selectively yielding β-keto sulfones and α-halo-β-keto sulfones in good to excellent yields with a wide tolerance of functional groups.

Synthesis of poly-functionalized imidazoles via vinyl azides annulation

An efficient annulation of vinyl azides with activated imines has been developed for the synthesis of poly-functionalized imidazole derivatives. This reaction includes thermal decomposition of vinyl azides to 2H-azirines, nucleophilic attack of 2H-azirines with activated imines and subsequent cyclization to desired imidazoles.

Highly efficient and eco-friendly protocol to functionalized imidazoles via ring-opening of α-nitro epoxides

A simple and direct synthesis of functionalized imidazoles from α-nitro-epoxides and amidines was developed. This reaction could proceed smoothly in a highly efficient and eco-friendly manner in moderate to excellent yields. A plausible mechanism has also been proposed.