The present invention in general relates to a novel compound, Vanillylidenechloroacetone (VCA), 1-Chloro-4-(4′-hydroxy-3′-methoxy-phenyl)-but-3-en-2-one. More specifically, the invention relates to a process to prepare VCA and use of the same in the synthesis of Calebin-A.
Calebin-A, also known as Feruloylmethyl ferulate, is a novel curcuminoid related structure obtained from rhizomes of Curcuma longa, of Zingiberaceae family. Calebin-A is naturally present in the rhizomes of Curcuma longa in trace amounts. It was first isolated and identified by Darrick S. H. L. Kim and So-Young Park (J. Nat. Prod., 2002, 65, 1227-1231) from Curcuma longa in 2001. Its analogs were synthesized by Kim, D. S. H. L. & Kim, J. Y. in 2001 (Bioorg. Med. Chem. Lett., 2001, 11, 2541-2543). Calebin-A has been reported to elicit various biological functions, some of which are mentioned in the following prior art documents:
There are many commercial processes available for the preparation of Calebin-A and its pharmaceutically acceptable salts. Calebin-A and its derivatives were isolated and synthesised by Yong et. al., (Chem. Pharm. Bull. 55 (6) 940-943 (2007)) and Majeed et. al., (Georg Thieme Verlag Stuttgart⋅New York—SynOpen 2017, 1, 125-128). Majeed et. al. also disclosed a process for the synthesis of Calebin-A and its biologically active analogs (U.S. Pat. No. 9,365,486).
However, the above processes either involves multi-steps or commercially not viable. Hence there is need to develop a commercially viable, safe, simple and scalable process for the large-scale production of Calebin-A and its analogs.
The present invention fulfils the aforesaid objectives by disclosing a simple, scalable, industrially advantageous and cost-effective process for the synthesis of Calebin-A. The invention also discloses a novel compound, Vanillylidenechloroacetone (VCA)—1-Chloro-4-(4-hydroxy-3-methoxy-phenyl)-but-3-en-2-one, used in the synthesis of Calebin A.
In the most preferred embodiment of the invention discloses a compound, Vanillylidenechloroacetone (VCA)—1-Chloro-4-(4′-hydroxy-3′-methoxy-phenyl)-but-3-en-2-one, as represented by STR#1 and the process of preparing the same.
In yet another preferred embodiment of the invention, the invention discloses a process to prepare Calebin-A from VCA.
Other features and advantages of the present invention will become apparent from the following more detailed description.
In the most preferred embodiment of the invention discloses a compound, Vanillylidenechloroacetone (VCA)—1-Chloro-4-(4′-hydroxy-3′-methoxy-phenyl)-but-3-en-2-one VCA, as represented by STR#1.
In another most preferred embodiment of the invention discloses a process to prepare VCA comprising steps of:
wherein VCA is isolated with a yield of not less than 40%.
In related embodiments of the invention, R in R3 (STR#2) is preferably alkyl, or more preferably aryl group, wherein alkyl group is C1-C4 linear or substituted, aryl group is either phenyl or substituted phenyl. In a preferred embodiment R is a phenyl group and in this preferred embodiment R3P is triphenylphosphine. In another related embodiment of the invention, above room temperature ranges from 35° C. to 70° C., and the time period ranges from 20 to 24 hours. In another preferred embodiment, the yield of VCA is in the range 40% to 60%. In another related embodiment of the invention, the aqueous base is selected from the group consisting of aqueous sodium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, or carbonates such as sodium carbonate, potassium carbonate, caesium carbonate, calcium carbonate, magnesium carbonate, sodium bicarbonate, potassium bicarbonate, or sodium methoxide, or potassium methoxide, or triethylamine, or tributylamine, or N-methylmorpholine, or N,N-diisopropylethylamine, or N-methylpyrrolidine, or pyridine, or collidine 4-(N,N-dimethylamino)pyridine, or morpholine, or imidazole, or 2-methylimidazole, or 4-methylimidazole. Any reference to processing in this embodiment (step c) refers to filtering, washing with methanol, and purification. The solvent in this embodiment includes protic or aprotic solvents, selected from the group consisting of water, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, diethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ether, diisopropyl ether, tert-butyl methyl ether, dibutyl ether, tetrahydrofuran, 1,2-dimethoxyethane, 2-methoxyethanol, 2-ethoxy ethanol, anisole, 1,4-dioxane, toluene, xylene, chlorobenzene, tetralin, chloroform, dichloromethane, DMF, acetic acid or mixtures thereof.
The choice of base and solvent are within the scope of those skilled in the art.
In yet another preferred embodiment of the invention, a process to prepare Calebin-A from VCA, comprising steps of:
Reacting 1-Chloro-4-(4′-hydroxy-3′-methoxy-phenyl)-but-3-en-2-one with ferulic acid at room temperature in a solvent in the presence of a base;
Isolating Calebin-A as represented by STR#3, from step a) with an yield of at least 80%.
In a related embodiment of the invention, the solvent is selected from the group consisting of protic or aprotic solvents, selected from the group consisting of water, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, diethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ether, diisopropyl ether, tert-butyl methyl ether, dibutyl ether, tetrahydrofuran, 1,2-dimethoxyethane, 2-methoxyethanol, 2-ethoxy ethanol, anisole, 1,4-dioxane, toluene, xylene, chlorobenzene, tetralin, chloroform, dichloromethane, DMF, acetic acid or mixtures thereof. In another embodiment, the base is preferably Alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide; carbonates such as sodium carbonate, potassium carbonate, caesium carbonate, calcium carbonate, magnesium carbonate, sodium bicarbonate, potassium bicarbonate, alkoxides such as sodium methoxide, potassium methoxide; organic bases, such as for example, triethylamine, tributylamine, N-methylmorpholine, N,N-diisopropylethylamine, N-methylpyrrolidine, pyridine, collidine 4-(N,N-dimethylamino)pyridine, morpholine, imidazole, 2-methylimidazole, 4-methylimidazole.
In another aspect of the invention, the yield is in the range 80% to 95%.
The choice of base and solvent are within the scope of those skilled in the art.
To a solution of 1,3-dichloroacetone (STR#5) (5 g, 0.0393 mol) in methanol (30.0 mL), charged triphenylphosphine (R=phenyl in the scheme, 8.26 g, 0.0314 mol) and stirred for 30 min at room temperature. The reaction mass was then heated to 60° C., maintained for 20 h and check the TLC. After the completion of reaction, cooled the reaction to room temperature, quench the reaction mass with 10% of aqueous sodium carbonate solution (15 ml) and maintain reaction for 12 h at room temperature. Filter the reaction mass and washed with aqueous methanol to afford 1-Chloro-3-(triphenyl-λ5-phosphanylidene)-propan-2-one (STR#4, Wittig ylid) (4.5 g, 98.48% HPLC) as pale white solid. Melting Point: 154-156° C., [M+H]+=353.
1H NMR (300 MHz, DMSO-d6): δ 4.11 (s, 2H), 7.45-7.75 (m, 15H).
13C NMR (100 MHz, DMSO-d6): 47.68, 129.53, 133.05, 183.86.
To a solution of vanillin (5 g, 0.0257 mol) in toluene (15.0 mL), charged 1-chloro-3-(triphenyl-λ5-phosphanylidene)-propan-2-one (STR#2) (6.54 g, 0.0515 mol) and stirred for 30 min at room temperature. The reaction mass was heated to 100-110° C., maintained for 15 h and cooled to room temperature. Add water (15 ml) and ethyl acetate (25 ml) to the above reaction mass and stirred for 30 mins. The organic layer (ethyl acetate+toluene) was washed with sodium bicarbonate solution (20 ml), followed by sodium chloride solution. Distilled the total ethyl acetate and isolated the solid in toluene and dried the compound under reduced pressure (vacuum) to yield 1-chloro-4-(4′-hydroxy-3′-methoxy-phenyl)-but-3-en-2-one (STR#1) as white solid. Yield: 3.5 g; 47% (Mp: 55-65° C.; [M+H]+=227)
1H NMR (300 MHz, DMSO-d6): δ 4.07 (s, 3H), 6.03 (s, 2H), 6.85-6.80 (d, J=15.0 Hz, 1H) 6.96-6.93 (d, J=9.0 Hz, 1H), 7.07-7.03 (d, J=7.5 Hz, 1H), 7.44-7.42 (d,1H), 7.67-7.62 (d, J=15.0 Hz, 1H).
13C NMR (100 MHz, DMSO-d6): 56.08, 115.76, 116.08, 120.40, 124.32, 125.93, 146.70, 145.15, 148.40, 150.35, 191.43.
To a solution of 1-Chloro-4-(4′-hydroxy-3′-methoxy-phenyl)-but-3-en-2-one (VCA, (STR#1)) (5 g, 0.0221 mol) in N,N-dimethyl formamide (15.0 mL), charged Ferulic Acid (STR#7) (4.3 g, 0.1221mol) & sodium bicarbonate (2.1 g, 0.02428) and stirred for 30 min at room temperature. The reaction mass was then heated to 50-55° C., maintained for 20 h and cooled to room temperature. After the completion of reaction, water (15 ml) and ethyl acetate (25 ml) were added to the above reaction mass. The separated organic layer was washed with sodium bicarbonate (20 ml) and brine solution. The ethyl acetate layer was distilled-off and diluted with toluene to afford solid. The resultant solid was filtered and dried at 80-85° C. for 15 h under reduced pressure to yield Calebin-A, 7 g, 81%.
1H NMR (Acetone,-d6, 300 MHz): δ 3.902 (s, 3H), 3.929 (s, 3H), 5.106 (s, 2H), 6.518 (d, J=15.9 Hz, 1H), 6.856 (d, J=16.2 Hz, 1H), 6.886 (d, J=8.4 Hz, 1H), 6.892 (d, J=8.4 Hz, 1H), 7.180 (dd, J=8.4 Hz, 1.8 Hz, 1H), 7.214 (dd, J=8.4 Hz, 1.8 Hz, 1H), 7.375 (d, J=1.8 Hz, 1H), 7.386 (d, J=1.8 Hz, 1H), 7.666 (d, J=16.2 Hz. 1H), 7.671 (d, J=15.9 Hz, 1H), 8.246 (s, 1H), 8.309 (s, 1H).
13C NMR (Acetone-d6, 75 MHz): δ 56.267, 56.296, 67.927, 111.290, 111.524, 116.077, 116.201, 120.322, 124.165, 124.494, 127.349, 127.408, 1.44.389, 146.505, 148.752, 150.209, 150.501, 166.898, 192.963.
While the invention has been described with reference to a preferred embodiment, it is to be clearly understood by those skilled in the art that the invention is not limited thereto. Rather, the scope of the invention is to be interpreted only in conjunction with the appended claims.
This application is a PCT filing claiming priority from U.S. provisional application No. 63/318,047 filed on 9 Mar. 2022, the contents of which are incorporated herein by reference.
Number | Date | Country | |
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63318047 | Mar 2022 | US |