Efficient synthesis of 4H-pyran derivatives using a polymeric catalyst based on PVP

One-pot multi-component process for the synthesis of 4-azaphenanthrene-3,10-dione, 1,8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives catalyzed by the deep eutectic solvent choline chloride-oxalic acid

“…Other ChCl-based DESs such as ChCl-malonic acid, ChCl-glycine, ChCl-citric acid and ChCl-urea were also examined. The results clearly show that ChCl-Ox is the optimal solvent and catalyst for the reaction (Table 1, entries [13][14][15][16][17]. It is worth to note that in a blank reaction without a catalyst (entry 18) only trace amounts of the corresponding product were obtained even after prolonged reaction times (2 h).…”

“…The acid-catalyzed condensation of dimedone with aromatic aldehydes to get 1,8-dioxo-octahydroxanthenes seems to be a highly efficient reaction [4,15]. It is worthy to mention that, with the addition of malononitrile to the reaction mixture, the preparation of tetrahydrobenzo[b]pyran scaffolds would be possible [16,17]. The conventional synthetic method for the preparation of 4-azaphenanthrene-3,10-diones involves a four-component condensation of Meldrum's acid, an aldehyde, primary amine or ammonium acetate and different 1,3-dicarbonyl compounds under different conditions [8,9].…”

Butane‐1‐sulfonic acid immobilized on magnetic Fe3O4@SiO2 nanoparticles: A novel and heterogeneous catalyst for the one‐pot synthesis of barbituric acid and pyrano[2,3‐d] pyrimidine derivatives in aqueous media

“…In recent years, the introduction of new catalysts for the promotion of organic reactions has become an important part of our ongoing research programme. [37][38][39] Based on the above mentioned difficulties in the preparation of 5arylidine barbituric acids and pyrano[2,3-d] pyrimidine derivatives and in continuation of our ongoing research programme on the introduction of new nanocatalysts for the promotion of organic reactions, we were interested in preparing, characterizing and studying the applicability of Fe 3 O 4 @SiO 2 -Sultone in the synthesis of these compounds. After preparation of the reagent as described in Section 2, it was characterized using various methods, and the obtained results are summarized in the following sections.…”

Graphene oxide‐bound electron‐deficient tin(IV) porphyrin: a highly efficient and selective catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane

“…By using HMDS, ammonia is produced as a by‐product but the disadvantage of HMDS is its low silylating ability in the absence of a suitable catalyst which increases the reaction times . To enhance the silylating power of HMDS, a variety of catalysts, including trichloroisocyanuric acid, silica‐supported perchloric acid, ZrCl 4 , K‐10 montmorillonite, LiClO 4 , H 3 PW 12 O 40 , iodine, InBr 3 , zirconium sulfophenylphosphonate, CuSO 4 ⋅5H 2 O, sulfonic acid‐functionalized nanoporous silica, MgBr 2 OEt 2 , LaCl 3 , poly( N ‐bromobenzene‐1,3‐disulfonamide) and N , N , N ′, N ′‐tetrabromobenzene‐1,3‐disulfonamide, Fe(TFA) 3 , Fe 3 O 4 , ( n ‐Bu 4 N)Br, ZrO(OTf) 2 , [Sn IV (TNH 2 PP)(OTf) 2 ]/CM‐MIL‐101, [Sn IV (TNH 2 PP)(OTf) 2 ]@CMP, [Sn IV (TPP)(OTf) 2 ], [Sn IV (TPP)(BF 4 ) 2 ], [V IV (TPP)(OTf) 2 ], Ru III (OTf)SalophenCH 2 –NHSiO 2 –Fe and [Ti IV (salophen)(OTf) 2 ], have been reported. Although these procedures provide an improvement, many of these catalysts need long reaction times, severe drastic reaction conditions or tedious workups, are moisture sensitive or are expensive.…”