Povarov-Reductive Amination Cascade to Access 6-Aminoquinolines and Anthrazolines

Abstract

A new strategy is reported for the synthesis of 6-aminoquinoline derivatives via a tandem Povarov reaction, dihydroquinoline oxidation, and imine reduction. These products allow access to symmetrical as well as unsymmetrical tetraarylpyrido[2,3-g]quinolines, potentially useful organic electronics.

Synthesis of Green/Blue Light Emitting Quinolines by Aza-D-A Reaction Using InCl3 Catalyst

“…Povarov reaction involves [4 + 2] cycloaddition reaction of Naryl imines with electron-rich dienophiles via activation of a terminal alkyne C-H bond and complexation of C-C multiple bonds to facilitate C-N and C-C bond formation, which are key intermediates for the construction of quinolines [20]. Recently, many metal salts like CuCl/AuCl [21] AuCl 3 / CuBr [22], Yb(OTf) 3 [23], Fe(OTf) 3 [24], Cu(OTf) 2 [25], Zn(OTf) 2 [26], AgNTf [27], NbCl 5 [28] are explored as effective Lewis acid catalytic system for quinoline synthesis though Povarov started with BF 3• OEt 2 in his original work [19]. Thus, the development of simple and efficient protocols for quinolines containing unique substituent from readily available starting materials is of great interest to organic chemists.…”

Expedient and Diastereoselective Synthesis of Substituted 6,6a-Dihydroisoindolo[2,1-a]quinolin-11(5H)-ones

“…16,17 Recently, we reported the synthesis of 5-substituted 6,6a-dihydroisoindolo[2,1-a]quinolin-11(5H)-ones by the [4+2] imino-Diels-Alder cyclization of N-aryl-3-hydroxyisoindolinones with N-vinyl lactams under BF 3 •OEt 2catalyzed anhydrous conditions. 18 In continuation of our previous studies on the development of various synthetic methodologies, [18][19][20][21][22][23][24] we have recently reported the synthesis of 3-substituted 2-arylisoindolin-1-ones in 56-96% yields from N-aryl-3-hydroxyisoindolinones and diverse alkyl aryl ketones such as acetophenones, 1-indanones, and α-tetralones in one step (C-C bond formation) under Lewis acid catalyzed microwave heating conditions (Scheme 1). 25 These reactions apparently involve the formation of N-acyliminium ion intermediate.…”

The Povarov Reaction: A Versatile Method to Synthesize Tetrahydroquinolines, Quinolines and Julolidines

“…14,136 Similarly to the synthesis of THQs, these reactions can be catalyzed by Lewis and Brønsted acids such as BF 3 •OEt 2 , 36,40,137-142 BF 3 •O(CH 3 ) 2 , 143,144 FeCl 3 , 145,146 InCl 3 , 147 trifluoromethanesulfonic acid, 148 p-toluenesulfonic acid, 146 CX4SO 3 H, 14,149 TFA, 150,151 camphorsulfonic acid, 152 tris(4-bromophenyl)aminium (TBPA + ), 140,[153][154][155] CBr 4 , 156 iron, 157 copper iodide 158 and iodine. [159][160][161][162][163][164][165][166][167] Furthermore, different triflates have been widely used such as Sc(OTf) 3 , 154,168,169 Yb(OTf) 3 , [170][171][172][173] Cu(OTf) 2 , 174,175 Ce(OTf) 3 , 176,177 Zn(OTf) 2 , 178 AgOTf, 22 In(OTf) 3 179 and Ca(OTf) 2 . 84 Heterogeneous catalysis was also described by using montmorillonite-supported perchloric acid (HClO 4 -Mont).…”