DABCO Catalyzed Synthesis of Xanthene Derivatives in Aqueous Media

Abstract

The reaction of 5,5-dimethylcyclohexane-1,3-dione with various heteroarylaldehydes afforded the corresponding heteroaryl substituted xanthene derivatives 1(a–f). The reaction proceeds via the initial Knoevenagel, subsequent Michael, and final heterocyclization reactions using 1,4-diazabicyclo[2.2.2]octane (DABCO) as a catalyst in aqueous media. The synthesized heteroaryl substituted xanthenes 1(a–f) reacted with malononitrile to obtain different alkylidenes 2(a–f). Short reaction time, environmentally friendly procedure, avoiding of cumbersome apparatus, and excellent yields are the main advantages of this procedure which makes it more economic than the other conventional methods.

Antioxidant, Antimicrobial and Antiproliferative Activities of Synthesized 2,2,5,5-Tetramethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione Derivatives

“…[19] When determining the antioxidant activity by using DPPH method, the absorbance of the 0.2 mM methanol solution of the test substance was mixed with the same ratio of 0.2 mM DPPH solution, representing the absorbance of the sample (AA (t)). The control solution is a mixture of methanol and DPPH.…”

“…The crude product was purified by recrystallization from 96 % ethanol. [19] Analytical data for synthesized 2,2,5,5-tetramethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones are listed below. 6.88 (t, 1H, J5′6′ = 7.9 Hz, J4′5′ = 7.8 Hz, H-5′); 13 …”

“…Then the intermediate B was cyclized by nucleophilic attack of the hydroxy group on the C=C moiety and 2,2,5,5-tetramethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones (1-10) were afforded. [19] According to described procedure we synthesized ten new 2,2,5,5-tetramethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione derivatives (1-10), that are structural analogues with different substituents at aryl ring (Table 1).…”

“…Mechanism of synthesis of 2,2,5,5-tetramethyl-9-aryl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones. [19] …”

Immobilized copper-layered nickel ferrite on acid-activated montmorillonite, [(NiFe2O4@Cu)(H+-Mont)], as a superior magnetic nanocatalyst for the green synthesis of xanthene derivatives

“…7 Moreover, some xanthene materials have been used as antagonists for paralyzing the action of zoxalamine 8 and dyes, [9][10][11] in laser technology, 12 as pH-sensitive uorescent agents 13 and as bactericides in agriculture. 14 30 [Hmim]TFA, 31 pdodecylbenzenesulfonic acid, 32 p-dodecylbenzenesulfonic acid/ ultrasound, 33 Dowex-50W, 34 amberlyst-15, 35 montmorillonite K10, 36 Fe 3+ -montmorillonite, 37 1,1,3,3-N,N,N 0 ,N 0 -tetramethylguanidinium triuoroacetate/TFA, 38 Et 3 (PhCH 2 )NBr, 39 TMSCl, 40 DABCO, 41 CuI/ poly(4-vinylpyridine), 42 graphene oxide-incorporated strontium NPs, 43 choline chloride/itaconic acid, 44 (NH 4 ) 2 HPO 4 , 45 and polyaniline-p-toluenesulfonate 46 1,8-dioxo-octahydroxanthenes have been prepared. In this context, some procedures involving Dowex-50W, 34 1,1,3,3-N,N,N 0 ,N 0 -tetramethylguanidinium triuoroacetate/TFA, 38 graphene oxide-incorporated strontium NPs, 43 choline chloride/ itaconic acid, 44 [Msim]Cl, 47 [Hmim] [HSO 4 ], 47 [Et 3 N-SO 3 4 ], 48 [Bmim] [BF 4 ], 49 Nsulfonic acid poly(4-vinylpyridinium) hydrogen sulfate, 50 p-toluene sulfonic acid, 51 amberlyst-15, 52 and FeCl 3 $6H 2 O 53 have also been reported for the preparation of 5H-dibenzo[b,i]xanthene tetraone materials.…”