Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• reactions between 2-aminobenzaldehydes 42 and β-nitrostyrenes 43 to obtain chiral 3-nitro-1,2-dihydroquinolines 45 in good yields with up to 98% ee (Table 9) [43]. 1.4 Reactions catalyzed by chiral phase-transfer catalysts Chiral phase-transfer catalysts (PTC) have been recognized as versatile catalysts for

• to good yield of 53–99% with an ee of 74–93% [54]. Liu et al. accomplished a catalytic cascade aza-Michael–Henry-dehydration protocol for the preparation of chiral 3-nitro-1,2-dihydroquinolines 83 from the reaction of N-protected aminobenzaldehydes 80 with substituted nitroolefins 81 by using

An intramolecular C–N cross-coupling of β-enaminones: a simple and efficient way to precursors of some alkaloids of Galipea officinalis

• Hana Doušová,
• Radim Horák,
• Zdeňka Růžičková and
• Petr Šimůnek

Beilstein J. Org. Chem. 2015, 11, 884–892, doi:10.3762/bjoc.11.99

• ). According to the literature [55], as well as the Cambridge Structural Database, there is a plethora of compounds with an intramolecular N–H···O=C contact like 1a; on the other hand, the family of structurally related 1,2-dihydroquinolines [56] and ethanones [57] is limited to only seven examples. In the

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• -dihydroisoquinolines 29, 35 and 36, respectively. The author suggested a mechanism that, starting from iminium intermediate 28, involves the nucleophilic addition on the electrophilic carbon atom of 28 and a protodemetalation yielding the desired 1,2-dihydroquinolines 29, 35 and 36. The annulation step giving rise to

• G–NH2 groups under palladium/copper [61][62], copper [63][64], copper/magnesium [65], or base [66] catalysis have been reported. When tosylhydrazide (41) is used as G–NH2 component, the silver promoted MCR can afford 2-amino-1,3-disubstituted-1,2-dihydroquinolines and, when the third component (Nu

• -pyrazolo[5,1-a]isoquinolines 48 under silver triflate catalysis (Scheme 26). The synthesis of both 1,2-dihydroquinolines 47 and 48 takes advantage from the easy formation of the isoquinolinium-2-ylamide 43 under silver triflate catalysis. This intermediate can be trapped by other nucleophilic reagents

Gold(I)-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl) ethers: synthesis of 3-iodo-2H-chromene derivatives

• Pablo Morán-Poladura,
• Eduardo Rubio and
• José M. González

Beilstein J. Org. Chem. 2013, 9, 2120–2128, doi:10.3762/bjoc.9.249

• competition with a direct Friedel–Crafts-type cyclization reaction yielding 3. In previous work dealing with the cyclization of N-(3-iodoprop-2-ynyl)-N-tosylanilines to give related 1,2-dihydroquinolines (Scheme 4A, X = NTs) [43], we documented for a phosphite-based gold-catalyst, which render a more

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

• Chittaranjan Bhanja,
• Satyaban Jena,
• Sabita Nayak and
• Seetaram Mohapatra

Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191

• -dihydroquinolines in optically enriched forms found in a myriad of bioactive natural products and synthetic compounds. Keywords: chromenes; 1,2-dihydroquinolines; enantioselective; Michael addition; organocatalytic; thiochromenes; Introduction Chromenes or benzopyrans and their sulfur and nitrogen analogues are

• six membered mono hetero-atom containing, biologically active heterocycles, such as functionalized chromenes (benzopyranes), thiochromenes (thiobenzopyranes) and 1,2-dihydroquinolines, by means of tandem/domino hetero Michael addition reactions, or modified versions [33][34][35][36][37][38], covering

• thiochromenes; and (3) Organocatalytic aza-Michael reactions to access functionalized 1,2-dihydroquinolines, using chiral proline and its derivatives (Figure 2), chiral bifunctional thioureas, cinchona alkaloids and other organocatalysts (Figure 3). For each reaction, the initial screening result of various

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• aziridines 174 (Scheme 30) [80]. Chan’s group developed an efficient synthetic route to 1,2-dihydroquinolines 177 via AuCl3/AgSbF6-catalyzed intramolecular allylic amination of 2-(tosylamino)phenylprop-1-en-3-ols 176 (Scheme 31) [81]. The mechanism is suggested to involve activation of the alcohol substrate