Palladium(0)-Catalyzed Asymmetric Synthesis of 1,2,3,4-Tetrahydro-2-vinylquinoxalines

Abstract

Reaction of (Z)‐1,2‐bis(methoxycarbonyloxy)but‐2‐ene (2) with various N,N‐bis(arylsulfonyl)‐o‐phenylenediamines 1 was catalyzed by a palladium complex associated with chiral ligands to give optically active 1,4‐bis(arylsulfonyl)‐1,2,3,4‐tetrahydro‐2‐vinylquinoxalines 3 with up to 62% ee. The use of (S)‐MeOBIPHEP as the chiral ligand and N,N‐bis(p‐tolylsulfonyl)‐o‐phenylenediamine (1i) as the nucleophile led to the highest ee at 25 °C, regardless of the solvent used. The enantioselectivity of the cyclization is strongly affected by the nature of the substituents at the nitrogen atom.

Sequential Synthesis, Olfactory Properties, and Biological Activity of Quinoxaline Derivatives

“…( S )-3-Hydroxymethyl-3,4-dihydro-1 H -quinoxalin-2-one 1j (0.8 g, 4.5 mmol), lithium aluminum hydride (1.2 g, 31 mmol), and dry THF (80 mL) were used: dark orange liquid; 587 mg, 79% yield; R f = 0.32 (hexanes/AcOEt = 1/4); [α] D 22 = −35.75 ( c 0.31, CHCl 3 ) (lit. [α] D 20 = −12.6 ( c 0.40, CHCl 3 ); 1 H NMR (400 MHz, CDCl 3 ) δ 6.64–6.56 (m, 2H, Ar), 6.55–6.48 (m, 2H, Ar), 3.66 (dd, J = 10.8, 4.8 Hz, 1H), 3.56 (dd, J =10.8, 6.8 Hz, 1H), 3.53–3.46 (m, 1H), 3.50 (brs, 2H, NH), 3.28 (dd, J = 10.8, 3.2 Hz, 1H), 3.16 (dd, J = 10.8, 6.0 Hz, 1H); 13 C NMR (100 MHz, CDCl 3 ) δ 133.1, 132.9, 119.2, 118.7, 114.9, 114.7, 64.6, 51.5, 42.6.…”

6 Nitrogen, phosphorus, arsenic, antimony and bismuth

“…The enantioselectivity of the cyclisation is strongly affected by the nature of the substituents at nitrogen. 27…”

Sustainable Palladium-Catalyzed Tsuji–Trost Reactions Enabled by Aqueous Micellar Catalysis

“…This led us to pursue the synthesis of various types of heterocycles via this method. Several cyclizations could be achieved under these aqueous conditions, each based on literature precedent in organic solvents . These cyclizations occurred smoothly at 1000 ppm of Pd catalyst, forming vinyl-substituted heterocycles such as piperazine, morpholine, dihydrofuran, and tetrahydrovinylquinoxaline-containing rings in typically moderate to high yields (Scheme ).…”