نتایج جستجو برای: heterocyclization
تعداد نتایج: 167 فیلتر نتایج به سال:
A highly efficient one-pot approach for the synthesis of carbonyl 2-amino-pyrimidines from 1,3-diynes and guanidine in the presence of Cs2CO3 and DMSO has been described. In these reactions, 1,3-diynes act as a precursor of buta-1,2,3-trienes and guanidine serves as the N-C[double bond, length as m-dash]N source for the construction of pyrimidines. This methodology proves to be a tandem regiose...
An enantioselective organocatalytic process for the one-step synthesis of poly-substituted 1,2,4-triazolines is reported. The heterocycle formation is believed to go through a step-wise mechanism of nucleophilic addition of an azlactone to an azodicarboxylate in the presence of an organic base catalyst, followed by a TMSCHN2 mediated heterocyclization. Both theoretical calculations and experime...
Heterocyclic rings are a recurring and iconic motif in organic chemistry. The introduction of five-membered rings into protein backbones is synthetically challenging, but many peptide-based biologically active natural products contain such Ser-, Thr-, and Cys-derived heterocycles and therefore a facile route to their introduction is highly desirable. More generally thiazolines and oxazolines, a...
The nitropolychlorobutadienes 3, 4 are valuable building blocks for various amination and successive heterocyclization products. Nucleophilic substitution reactions of the partially protected, bioactive amines 1, 2 with either vinyl, imidoyl or carbonyl chlorides result in the formation of the enamines 11, 12, 13, 16, 25, the amidine 6, and the amides 20, 21, respectively. In the following, cyc...
A new domino strategy for the synthesis of highly functionalized quaternary imidazole derivatives via [3 + 2] heterocyclization, involving aryl migration and ring-opening of oxirane, has been developed. This domino reaction enables the successful assembly of three new sigma bonds including two C-N bonds in a simple operation. Features of this strategy include the mild conditions, convenient ope...
The reaction of cyanoacetyl hydrazine (1) with 3-acetylpyridine (2) gave the hydrazide-hydrazone derivative 3. The latter compound undergoes a series of heterocyclization reactions to give new heterocyclic compounds. The antitumor evaluation of the newly synthesized products against three cancer cell lines, namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS canc...
A new total synthesis of the alkaloid variolin B is achieved by a selective and sequential palladium-mediated functionalization of a trihalo-substituted pyrido[30,20:4,5]pyrrolo[1,2-c]pyrimidine. This intermediate is obtained by a new heterocyclization reaction between an appropriate bromomethyl azaindole and N-tosylmethyl dichloroformimide. The methodology may be effective for the synthesis of...
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