Yb(OTf)3-Mediated Annulation of Cyclopropane-1,1-dicarbonitriles with 2-Aminobenzaldehydes for Synthesis of Polysubstituted Quinolines

Annulation of 2-Aroyl D-A Cyclopropanes via Selectively Ring-Opening Process with o-Benzenediamines to Access Quinoxaline Derivatives

An annulation reaction of 2-aroyl D-A cyclopropanes with o-benzenediamines via selective cleavage of C-C bonds of cyclopropane in the presence of DBU/Sc(OTf)3 reaction systems was developed for the direct preparation of 2-aryl-3-benzylquinoxalines. This synthetic approach tolerated a wide range of readily available aroyl-substituted D-A cyclopropanes with diverse functional groups and had operationally simple and mild reaction conditions.

Aniline assisted dimerization of phenylalanines: convenient synthesis of 2-aroyl-3-arylquinoline in an I2-DMSO system

We herein report an efficient synthesis of 2-aroyl-3-arylquinolines from phenylalanines and anilines. The mechanism involves I₂-mediated Strecker degradation enabled catabolism and reconstruction of amino acids and a cascade aniline-assisted annulation. Both DMSO and water act as oxygen sources in this convenient protocol.

Cu-Catalyzed Decarboxylative Annulation of N-Phenylglycines with Maleimides: Synthesis of 1H-Pyrrolo[3,4-c]quinoline-1,3(2H)-diones

A novel protocol for the construction of functionalized 1H-pyrrolo[3,4-c]quinoline-1,3(2H)-diones (PQLs, 3) from N-phenylglycines and maleimides was developed. The cascade reaction was enabled by heating a mixture of the two substrates in the presence of di-tert-butyl peroxide (DTBP) as an oxidant and anhydrous CuBr as a catalyst in chlorobenzene. Consequently, a diverse series of PQLs 3 were synthesized in moderate-to-good yields (43-73%). The synthesis of the PQLs was enabled via a one-pot cascade reaction that proceeded through subsequent oxidative decarboxylation, 1,2-addition, intramolecular cyclization, tautomerization, and aromatization reactions. This protocol can be used for the synthesis of functionalized PQLs via a one-pot oxidative decarboxylation annulation reaction rather than through a series of multistep reactions, making it suitable for both combinatorial and parallel syntheses of PQLs.

Acetic Acid Mediated Regioselective [3 + 3] Cycloaddition of Substituted Cyclopropane-1,1-dicarbonitriles with 1,4-Dithiane-2,5-diol

An acetic acid mediated regioselective [3 + 3] cycloaddition of substituted cyclopropane-1,1-dicarbonitriles with in situ generated mercaptoacetaldehyde was developed for the synthesis of highly stereoselective tetrahydrothiopyranols. This transformation created two new bonds in a single operation for generating complexity in tetrahydrothiopyrans. This method is characterized by cheap and readily available starting materials, simple operation, and mild reaction conditions.

tert-Butyl Hydroperoxide Promoted the Reaction of Quinazoline-3-oxides with Primary Amines Affording Quinazolin-4(3H)-ones

An efficient and facile approach for the synthesis of quinazolin-4(3H)-ones via the reaction of quinazoline-3-oxides with primary amines is described. This approach is demonstrated to be applicable for a broad range of substrates and proceeds efficiently under metal-free and mild reaction conditions employing easily available tert-butyl hydroperoxide as the oxidant. Remarkably, 3-(2-(1H-indol-3-yl) ethyl)quinazolin-4(3H)-one 3w, which was conveniently obtained by this process in 70% yield, was an excellent precursor for the synthesis of bioactive evodiamine and rutaempine.