Amberlyst-15 catalyzed Povarov reaction of N-arylidene-1H-indazol-6-amines and indoles: a greener approach to the synthesis of exo-1,6,7,7a,12,12a-hexahydroindolo[3,2-c]pyrazolo[3,4-f]quinolines as potential sirtuin inhibitors

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.…”

“…described by the use of bovine pancreas -chemotrypsin in aqueous acetonitrile 86 with a strong preference towards the trans diastereoisomers, whereas other enzymes such as papain, lipases, and amylases failed to provide the THQ. Concerning the reaction medium, polar solvents such as acetonitrile 34,37,41,45,47,51,54 and alcohols 53,65,87,88 were the most typical, but not a requirement since apolar solvents including dichloromethane, 35,74,89 dichloroethane 28,60,90 and toluene 78,91,92 were also well represented in the literature. Fluorinated alcohols, such as hexafluoroisopropanol (HFIP) 71 and trifluoroethanol (TFE) 50,93 can be employed to dissolve reagents that are insoluble in the most common solvents, 71 or can even act as the catalyst itself, thereby removing the requirement for the addition of acids.…”

Recent Studies of Bifunctionalization of Simple Indoles

“…The in situ generation of imines could be catalyzed by metals, Brønsted acids, Lewis acids or by organo‐catalyst, and be trapped by indole at C3 position [1b] . For example, aryl imines [13a,b] were able to construct quinoline derivatives via Lewis acid‐catalyzed addition and cyclization. For example, the Wang group [13a] discovered a mild three‐component reaction of aryl aldehydes, amines, and indoles, with iodine as catalyst.…”

Combinatorial Chemistry Online Volume 17, Issue 7, July 2015

“…Representative candidates from the library of exo-1,6,7,7a,12, 12a-hexahydroindolo [3,2-c]pyrazolo [3,4-f]quinolines thus produced were tested for their sirtuin (Sir-2) inhibitory activity using a yeast-based assay [8].…”