SnCl₂-Catalyzed Selective Atom Economic Imino Diels–Alder Reaction: Synthesis of 2-(1H-Pyrrolo[2,3-b]pyridin-3-yl)quinolines

Abstract

The synthesis of 2-(1H-pyrrolo[2,3-b]pyridin-3-yl)quinolines by a SnCl(2)-catalyzed multicomponent reaction has been described. The reaction proceeds chemo- and regioselectively in an atom-economic way, generating a library of 24 quinoline derivatives.

Synthesis of Polybenzoquinolines as Precursors for Nitrogen‐Doped Graphene Nanoribbons

“…[11][12][13] Here,t o enable the formation of awell-defined nitrogen-doped GNR, we designed an alternative unreported precursor consisting of benzoquinoline subunits linked at their 4a nd 6p ositions (Figure 1, middle). We in turn drew inspiration from the synthesis of quinoline heterocycles via the aza-Diels-Alder (Povarov) reaction [38][39][40][41][42][43][44] and pictured the construction of the benzoquinoline subunits from alkyne-and aldimine-modified monomers (Figure 1, right). Consequently,wepostulated that polymerization of the bifunctional monomers would furnish the desired polybenzoquinoline precursor (Figure 1, middle), which could ultimately be cyclodehydrogenated into an itrogen-doped N = 7a rmchair GNR (Figure 1, left).We began our studies by synthesizing benzoquinoline model compounds 3a,b and 5a,b via the Povarov reaction, [38][39][40][41][42][43][44] as illustrated in Scheme 1a.T op repare model compounds 3a and 3b,w ef irst formed aldimines 1a and 1b by using ak nown literature protocol.…”

“…We in turn drew inspiration from the synthesis of quinoline heterocycles via the aza-Diels-Alder (Povarov) reaction [38][39][40][41][42][43][44] and pictured the construction of the benzoquinoline subunits from alkyne-and aldimine-modified monomers (Figure 1, right). Consequently,wepostulated that polymerization of the bifunctional monomers would furnish the desired polybenzoquinoline precursor (Figure 1, middle), which could ultimately be cyclodehydrogenated into an itrogen-doped N = 7a rmchair GNR (Figure 1, left).We began our studies by synthesizing benzoquinoline model compounds 3a,b and 5a,b via the Povarov reaction, [38][39][40][41][42][43][44] as illustrated in Scheme 1a.T op repare model compounds 3a and 3b,w ef irst formed aldimines 1a and 1b by using ak nown literature protocol. [45] We then reacted naphthyl alkyne 2 with 1a or 1b in the presence of BF 3 ·OEt 2 as the Lewis acid mediator and chloranil as the sacrificial oxidant, [46][47][48][49][50] producing benzoquinolines 3a or 3b,r espectively.N ext, to prepare model compounds 5a and 5b,w e [*] Dr.…”

“…We began our studies by synthesizing benzoquinoline model compounds 3a,b and 5a,b via the Povarov reaction, [38][39][40][41][42][43][44] as illustrated in Scheme 1a.T op repare model compounds 3a and 3b,w ef irst formed aldimines 1a and 1b by using ak nown literature protocol. [45] We then reacted naphthyl alkyne 2 with 1a or 1b in the presence of BF 3 ·OEt 2 as the Lewis acid mediator and chloranil as the sacrificial oxidant, [46][47][48][49][50] producing benzoquinolines 3a or 3b,r espectively.N ext, to prepare model compounds 5a and 5b,w e converted the pendant bromides of compounds 3a and 3b to alkynes,f orming 4a and 4b,r espectively.W et hen reacted alkyne 4a with aldimine 1a,p roducing benzoquinolines 5a, and alkyne 4b with aldimine 1b,p roducing benzoquinoline 5b.T his linear synthetic strategy furnished the desired regioisomerically pure products in moderate yields.…”

Palladium‐Catalyzed Decarboxylative Suzuki and Heck Couplings of Azaindole‐2‐carboxylic Acids: Synthesis of 2‐Aryl/Alkenyl‐1‐phenylsulfonyl‐1 H‐pyrrolo‐[2,3 b]pyridines

“…[10] As part of our continuing interest in indoles, [11] a system with an azaindole unit was selected as a starting point. Azaindole is an important subclass of indole and is present in wide range of bioactive compounds.…”

SnCl2/EtOH-Mediated Synthesis of Novel 4-Ethoxy- and 4-Chloroindazoles Bearing Sulfonamide Moieties

“…In recent years, stannous chloride has been receiving increasing interest as reducing agent due to its applications in organic transformations [1][2][3][4][5] . In view of its inherent properties such as reusability, greater selectivity, operational simplicity, non-corrosiveness, low cost and ease of isolation, several groups have accomplished efficient syntheses of different heterocyclic compounds employing the reduction of nitro derivatives with stannous chloride [6][7][8][9] .…”