RESUMEN
We present an efficient approach for synthesizing pyridoquinazolinones in the presence of triflic anhydride utilizing anthranils and 2-chloropyridines as starting materials. In this process, Tf2O initially activates anthranils forming an electrophilic 1-((trifluoromethyl)sulfonyl)benzo[c]isoxazol-1-ium species. This species undergoes an in situ annulation reaction with 2-chloropyridines, resulting in therapeutically useful pyridoquinazolinones. The reaction is tolerant to various functional groups, allowing access to a wide range of substituted pyridoquinazolinones in good yields. Furthermore, the synthesis of euxylophoricine B, known to be an antitumor agent, was also achieved.
RESUMEN
The palladium-catalyzed oxidative C3-alkenylation of anthranils (2,1-benzisoxazoles) with various styrenes has been successfully achieved. The C3-alkenylated anthranils were subsequently utilized in a [4+2]-cycloaddition with in situ generated α,ß-unsaturated ketones leading to the synthesis of a diverse range of olefin-containing quinolines. Notably, this reaction exclusively yielded mono-alkenylated products with E-selectivity. The optimized catalytic conditions were compatible with a wide variety of substituted olefins and anthranils, forming various C3-alkenylated anthranils with good yields. To showcase the application of the present methodology, the C3-alkenylated anthranils have been employed as synthons to access a wide range of substituted quinolines.
RESUMEN
An acid-mediated and DMSO participant one-pot tandem synthesis of 3-substituted-1-aryl-1H-pyrazolo-[3,4- b]quinoline from readily available anilines and pyrazolones was achieved. This method enables regioselective construction of the valuable heterocycles under transition-metal and oxidant-free conditions in which DMSO acts as a methine source as well as solvent making this process an environmentally benign approach. A broad range of diversely substituted aryl amines and pyrazolines are successfully employed in this reaction to access a series of pyrazolo[4,3-c]quinolones through a novel cascade mechanism. Furthermore, the application and mechanistic studies of the present methodology also demonstrated.
Asunto(s)
Pirazolonas , Quinolinas , Aminas , Compuestos de Anilina , Dimetilsulfóxido , HumanosRESUMEN
A new one-pot, transition-metal, acid/base-free domino process is developed for the regioselective synthesis of 1,2,4-trisubstituted pyrroles. The process involves 1,3-dipolar cycloaddition of unsymmetrical azomethine ylide resulting from the thermal C-C bond cleavage of unactivated aziridines with ß-bromo-ß-nitrostyrene, followed by a cascade of elimination and aromatization reaction sequence to preferentially furnish 1,2,4-trisubstituted pyrroles instead of the expected 1,2,3-trisubstituted pyrroles, in good to excellent yields. Further, the application of the methodology for the formal synthesis of ningalin B is delineated.
RESUMEN
Short and scalable total syntheses of lamellarin G trimethyl ether, lamellarin D trimethyl ether, lamellarin H, lamellarin η, dihydrolamellarin η, and lamellarin U have been realized in four to six linear steps with an overall yield of ≤22%. Highlights of the synthesis include single-step access to the central 1,2,4-trisubstituted pyrrole core in a highly regioselective manner via a one-pot [3+2] cycloaddition/elimination/aromatization sequence-based domino process. Subsequent, palladium-mediated double C-H oxidative coupling in a single-pot operation provides access to the pentacyclic coumarin-fused pyrrolo-dihydroisoquinoline core present in lamellarins.
