Facile synthesis of functionalized tetrahydroquinolines via domino Povarov reactions of arylamines, methyl propiolate and aromatic aldehydes

• Jing Sun,
• Hong Gao,
• Qun Wu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2012, 8, 1839–1843, doi:10.3762/bjoc.8.211

• reaction; tetrahydroquinoline; Introduction The Diels–Alder reaction is recognized as a powerful reaction in synthetic strategies for the production of natural and unnatural polycarbocycles and polyheterocycles [1][2][3]. Therefore, the hetero-Diels–Alder reactions and domino reaction procedures have been

• enantiomerically enriched 4-amino-tetrahydroquinolines [43][44]. In this work our aim is to describe the domino Povarov reaction with both in situ formed aldimine and in situ generated β-enamino ester for the facile synthesis of the functionalized tetrahydroquinoline. Results and Discussion It is known that the

• overnight to give the desired β-enamino ester. Then, benzaldehyde and p-toluenesulfonic acid was introduced in the reaction system and the sequential reaction was finished in 48 hours at room temperature monitored by TLC. After workup we were pleased to find that the functionalized tetrahydroquinoline 1c

Organocatalytic C–H activation reactions

• Subhas Chandra Pan

Beilstein J. Org. Chem. 2012, 8, 1374–1384, doi:10.3762/bjoc.8.159

• (−)-camphorsulfonic acid (CSA) in 1,1,2-trichloroethane (TCE) at 20 °C provided the desired product in highest enantioselectivity (89% ee). Under the optimized conditions, a range of ortho-(dialkylamino)cinnamaldehydes were employed and chiral tetrahydroquinoline products 14 were obtained in moderate to good yields

• excellent enantioselectivities (70–97% ee, mostly above 90% ee) were achieved for different tetrahydroquinoline products 16 having gem-methyl ester groups (Scheme 12). For substrates containing one N-benzyl group and one N-ethyl group, binaphthol-based catalyst 17 was used; however, no chemoselectivity (16j

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

• Magnus Rueping,
• Teerawut Bootwicha and
• Erli Sugiono

Beilstein J. Org. Chem. 2012, 8, 300–307, doi:10.3762/bjoc.8.32

• increasing the residence time to 60 min (Table 3, entry 3 versus entry 2). The catalyst loading can be decreased to 0.5 mol % without loss of reactivity and selectivity; the desired tetrahydroquinoline was isolated in 96% yield with 94% enantiomeric excess (Table 3, entry 5). A further decrease of catalyst

Multicomponent reaction access to complex quinolines via oxidation of the Povarov adducts

• Esther Vicente-García,
• Rosario Ramón,
• Sara Preciado and
• Rodolfo Lavilla

Beilstein J. Org. Chem. 2011, 7, 980–987, doi:10.3762/bjoc.7.110

• the starting tetrahydroquinoline, such as O-, N- and C-linked residues (Scheme 2) [8][9][12][13][16][17][18]. Unfortunately, the alternative oxidation–elimination products (5 and 8) are often observed, therefore suggesting an acid catalyzed process. This would account for the elimination of alcohol

• , commercial reagents and additives on the oxidation of an elimination-prone Povarov tetrahydroquinoline substrate. In this way, tetrahydroquinolines 17,17' were synthesized as a mixture of isomers from the enol ether 14, p-bromoaniline (15) and p-chlorobenzaldehyde (16) under Sc(OTf)3 catalysis using standard

• ]+ calcd for C18H16BrClNO, 376.0098; found, 376.0090. Optimization of the reaction conditions for the preparation of quinoline 18. Povarov oxidation access to substituted quinolines. Tetrahydroquinoline oxidation. Synthesis of the Povarov adducts and their oxidation products. Oxidation of lactam-fused

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

• Franca M. Cordero,
• Carolina Vurchio,
• Stefano Cicchi,
• Armin de Meijere and
• Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

• Discussion The tetrahydropyridones employed in this study were prepared according to published procedures with slight modifications. In particular, oxidation of the tetrahydroquinoline 5 with oxone [38] afforded the nitrone 6 [39][40][41] in 66% yield (Scheme 2, see Supporting Information File 1 for full