Benzo[b]Furan in the Povarov Reaction

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

“…The Povarov reaction and its variants can be catalyzed by a wide variety of Brønsted and Lewis acids: BF 3 ·Et 2 O, 33 34 35 36 37 38 39 40 BiCl 3 , 41–44 CAN, 45 46 47 48 49 50 51 cerium sulfate, 52 Amberlyst 15, 53 phthalic acid, 54 p -toluenesulfonic acid 55 56 and its supramolecular analogue CX4SO 3 H, 57 ferric sulfate, 58 59 60 iodine, 61 62 63 InCl 3 , 64 65 66 67 68 69 NH 4 Br, 70 Sc(OTf) 3 , 71 72 73 74 75 and Sc(III)-loaded resin, 76 Y(OTf) 3 , 77 78 79 80 81 bistriflimide, 28 TFA 82 and zinc chloride. 83 Moreover, mixed catalytic systems may be employed, such as Ca(OTf) 2 /Bu 4 NPF 6 84 and CeCl 3 /NaI.…”

“…The main coordination point is with the nitrogen of the imine, which activates the C=N bond. The second coordination point is dependent upon the structure of the dienophile and the imine: if a hydrogen donor group is present on the imine, double activation on the imine may happen (40) or with a dienophile's hydrogen-donating group, if present, activating both substrates (41). 119 Dedicated reviews on stereoselective Povarov syntheses of THQs are available.…”

“…1 8 When no oxidizing agent is added to the reaction medium, O 2 (air) is the final oxidant. 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 , 137 138 139 140 141 142 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 .…”

Metal Free Synthesis of Coumarin Containing Hetero[n]helicene like Molecules with TICT and AIE Properties

“…Povarov reaction is three component reaction in which aromatic amines initially form aldimines with aldehydes and then undergo [4+2] cycloaddition reaction with a variety of substrates including alkyne, alkene, cyclic alkene, enol (ketone, cyclic ketone) [39–40] . Three component Povarov reaction of aniline, naphthalene‐2‐amine, and heterocyclic amines derivatives have been reported and well explored for the synthesis of tetrahydroquinoline/ quinolone derivatives using various Lewis acid such as BF 3 ⋅ OEt 2 , Yb(OTf) 3 , Sc(OTf) 3 , etc [41–48] . Povarov reaction of 3‐amino coumarin has been reported using different catalysts such as metal triflates (lanthanide triflates, copper triflates), Lewis acid (BF 3 ⋅ OEt 2 , I 2 ), Brønsted acids (MsOH, TFOH) [49–55] .…”

“…[39][40] Three component Povarov reaction of aniline, naphthalene-2-amine, and heterocyclic amines derivatives have been reported and well explored for the synthesis of tetrahydroquinoline/ quinolone derivatives using various Lewis acid such as BF 3 • OEt 2 , Yb(OTf) 3 , Sc(OTf) 3 , etc. [41][42][43][44][45][46][47][48] Povarov reaction of 3-amino coumarin has been reported using different catalysts such as metal triflates (lanthanide triflates, copper triflates), Lewis acid (BF 3 • OEt 2 , I 2 ), Brønsted acids (MsOH, TFOH). [49][50][51][52][53][54][55] We have designed and synthesized coumarin containing hetero [n]helicene like molecules to study their photophysical properties.…”