Synthesis of quinolines and naphthyridines via catalytic retro-aldol reaction of β-hydroxyketones with ortho-aminobenzaldehydes or nicotinaldehydes

Synthesis of Indenoquinolinones and 2-Substituted Quinolines via [4 + 2] Cycloaddition Reaction

We have reported a metal-free protocol for the synthesis of indenoquinolinones and 2-substituted quinolines via [4 + 2] cycloaddition reaction using readily available 2-aminobenzaldehydes and ketones as starting materials. Different quinoline derivatives can be selectively synthesized by changing the type of ketones. O₂ and dimethyl sulfoxide (DMSO) as co-oxidants play an important role in the synthesis of indenoquinolinones. This condensation/oxidation strategy involves the formation of C-N, C-C, and C-O bonds, with the advantages of high yields and a broad substrate range.

Photocatalytic Synthesis of Quinolines via Povarov Reaction under Oxidant-Free Conditions

We describe here an approach for synthesizing quinolines either from N-alkyl anilines or from anilines and aldehydes. A dual-catalyst system consisting of a photocatalyst and a proton reduction cocatalyst is employed. Without the use of any sacrificial oxidant and under extremely mild conditions, the reactions afford quinolines in excellent yields and produce H₂ as a byproduct.

Crystal structure of 4-methoxyphenyl-3-phenylpropiolate, C16H12O3

C16H12O3, orthorhombic, Pbca (no. 19), a = 3.9935(16) Å, b = 16.629(7) Å, c = 19.406(8) Å, V = 1288.7(9) Å3, Z = 4, Rgt(F) = 0.0387, wRref(F2) = 0.1084, T = 296(2) K.

Crystal structure of 2-(naphthalen-2-yl)-1,8-naphthyridine, C18H12N2

C18H12N2, monoclinic, P21/c (no. 14), a = 27.514(5) Å, b = 6.3231(11) Å, c = 7.4175(13) Å, β = 95.805(2)°, V = 1283.8(4) Å3, Z = 4, R gt(F) = 0.0439, wR ref(F 2) = 0.1233, T = 296(2) K.

Crystal structure of (2E,4Z)-dimethyl 4-((phenylamino)methylene)pent-2-enedioate, C14H15N1O4

C14H15N1O4, triclinic, P1̄, a = 8.2018(4) Å, b = 11.5512(5) Å, c = 14.4121(7) Å, α = 79.242(2)°, β = 78.647(3)°, γ = 85.496(3)°, V = 1313.93(11) Å3, Z = 2, R gt(F) = 0.0548, wR ref(F 2) = 0.1805, T = 296(2) K.

Crystal structure of 2-(4-chlorophenyl)-3-phenyl-1,8-naphthyridine, C20H13N2Cl

C20H13N2Cl, monoclinic, P21/n (no. 14), a = 6.179(4) Å, b = 11.666(8) Å, c = 22.460(15) Å, β = 95.837°, V = 1610.6(19) Å3, Z = 4, Rgt(F) = 0.0507, wRref(F2) = 0.1599, T = 296(2) K.

Crystal structure of 2-(3,4-dimethylphenyl)-1,8-naphthyridine, C16H14N2

C16H14N2, orthorhombic, P212121, a = 6.449(8) Å, b = 10.548(14) Å, c = 17.84(2) Å, V = 1213(3) Å3, Z = 4, R gt(F) = 0.0406, wR ref(F 2) = 0.0933, T = 296(2) K.

Preparation of Polyfunctional Naphthyridines by Cobalt-Catalyzed Cross-Couplings of Halogenated Naphthyridines with Magnesium and Zinc Organometallics

CoCl₂ (5%) catalyzes cross-couplings of various halogenated naphthyridines with alkyl- and arylmagnesium halides. Also, arylzinc halides undergo smooth cross-couplings with various naphthyridines in the presence of CoCl₂·2LiCl (5%) and sodium formate (50%), leading to polyfunctional arylated naphthyridines. Two of these arylated naphthyridines are highly fluorescent, with quantum efficiencies reaching 95% and long excited-state lifetimes of up to 12 ns.

Chemoselective C(α)–C(β) bond cleavage of saturated aryl ketones with amines leading to α-ketoamides: a copper-catalyzed aerobic oxidation process with air

An unprecedented chemoselective C(α)–C(β) bond cleavage of simple saturated aryl ketones with amines leading to α-ketoamidesvia a copper-catalyzed aerobic oxidation process with air has been disclosed.

Divergent synthesis of indoles, oxindoles, isocoumarins and isoquinolinones by general Pd-catalyzed retro-aldol/α-arylation

Divergent synthesis of indoles, oxindoles, isocoumarins and isoquinolinones is achieved by a general Pd-catalyzed retro-aldol reaction of β-hydroxy ketones/esters with aryl halides bearing an ortho-nitro, -ester or -nitrile group. DFT insights have been presented to rationalize the experimental observations and the chemoselectivity.