CAREBASTINE

Molecular Weight	499.64
Appearance	Solid
Formula	C₃₂H₃₇NO₄
CAS No.	90729-42-3

Carebastine is the active metabolite of Ebastine. Carebastine is a histamine H1 receptor antagonist. Carebastine inhibits VEGF-induced HUVEC and HPAEC proliferation, migration and angiogenesis in a dose-dependent manner. Carebastine suppresses the expression of macrophage migration inhibitory factor.

Carebastine is the active metabolite of Ebastine. Carebastine is a histamine H1 receptor antagonist. Carebastine inhibits VEGF-induced HUVEC and HPAEC proliferation, migration and angiogenesis in a dose-dependent manner^[1]. Carebastine suppresses the expression of macrophage migration inhibitory factor^[2].

Literature References: Nonsedating type histamine H1-receptor antagonist. Prepn: J. M. P. Soto et al., EP 134124; eidem, US 4550116 (both 1985 to Fordonal). Metabolized in vivo to carebastine, its active carboxylic acid metabolite.

PATENT

https://patents.google.com/patent/US8067604B2/en

These schemes also illustrate the interrelatedness of the processes and intermediates.

EXAMPLE 1

One gram of 9 was dissolved in 20 mL of DMF and 18 mg of P(tBu)₃, 41 mg of Pd(dba)₂, 230 mg of ZnF₂and 1.2 g of 5 were added. A mixture was stirred at 80° for 18 hours, cooled to room temperature, diluted with ether and washed with water. The organic layer was dried over sodium sulfate, filtered and stripped in vacuo. The resulting product was flash chromatographed on silica gel using 4:1 hexane ethyl acetate to yield 1.0 g (91%) of 10. A repeat of the reaction on larger scale using 15 g of 9 provided 15.2 g (93%) of 10.

EXAMPLE 2

Five grams of 9 was dissolved in 50 mL of methylene chloride and cooled to 0° C. To the solution was added 5.78 g of trimethylsilyl iodide. The mixture was stirred for 30 minutes and excess sodium bisulfite solution was added with vigorous stirring at room temperature. The layers were separated and the aqueous layer extracted twice with methylene chloride. Combined organic layers were dried, filtered and stripped in vacuo to provide 7.7 g (98%) of 1. The reaction was repeated on a larger scale using 15 g of 9 to produce 22.5 g of 1 (96%) yield.

EXAMPLE 3

Six grams of potassium carbonate, 5.8 g of piperidine 2 and 7.6 g of 1 are combined in 100 mL of DMF. The suspension is stirred at room temperature until TLC in 4:1 hexane-ethyl acetate indicates a complete reaction. The reaction mixture is poured into 400 mL of water and extracted three times with methylene chloride. The combined organic extracts are dried, filtered and reduced in vacuo. The resulting product is flash chromatographed on silica gel using ethyl acetate containing 10% triethylamine to yield 3.

EXAMPLE 4

Seven grams of 3 is dissolved in 100 mL of methanol, cooled to 0° C. and 1.1 g of sodium borohydride is added. The mixture is stirred 1 hour, concentrated and partitioned between ethyl acetate and saturated aqueous sodium bicarbonate. The bicarbonate layer is extracted twice with ethyl acetate, the combined organic layers are dried over sodium sulfate and the solution is reduced in vacuo to provide 4.

EXAMPLE 5

Two grams of 4 is dissolved in 30 mL of DMF. To this are added 16.2 mg of P(tBu)₃, 36.6 mg of Pd(dba)₂, 209 mg of ZnF₂and 1.056 g of 5. The mixture is heated at 80° C., cooled, diluted with ether and worked up as in example 1. The resulting product is flash chromatographed on silica gel using 9:1 ethyl acetate-triethylamine to provide 7.

EXAMPLE 6

One hundred fifty milligrams of 6 is slurried in 5 mL of water and 10 mL of methanol. To the slurry is added 175 mg of sodium hydroxide. The slurry is refluxed for one hour, cooled to room temperature and the methanol removed in vacuo. The resulting aqueous solution is distributed between water and chloroform, the chloroform layer is discarded, the aqueous layer is adjusted to pH 2.3 and extracted with chloroform. The organic layer is dried, filtered and reduced in vacuo to provide carebastine.

EXAMPLE 7

Five grams of 1 was combined with 2.64 g of 2 and 2.0 g of potassium carbonate and 80 mL of DMF. The mixture was stirred at room temperature for two hours, poured into 400 mL of water and extracted three times into methylene chloride. The combined organic layers were dried, filtered and reduced in vacuo. The resulting product was flash chromatographed on silica gel using 9:1 ethyl acetate-triethylamine to provide 2.0 g (54%) of 3.

EXAMPLE 8

One and seven-tenths grams of 3, 90 mg of P(tBu)₃, 300 mg of Pd(dba)₂, 250 mg of ZnF₂and 1.1 g of 5 were dissolved in 330 mL of DMF under argon. The mixture was heated to 80° for two hours, cooled to room temperature, diluted with ether and worked up as described in example 1. The resulting product was filtered through silica to provide 1.2 g (67.8%) of 6.

EXAMPLE 9

Two grams of 20, 170 mg of P(tBu)₃, 560 mg of Pd(acac)₂, 474 mg of ZnF₂and 2.0 g of 5 were combined in 50 mL of DMF under argon. The mixture was heated to 80° C. and monitored by HPLC. When reaction was complete, the mixture was cooled to room temperature and 250 mL of water was added. The mixture was extracted three times with ether, dried, filtered and reduced in vacuo. The resulting product was flash chromatographed in 4:1 hexane-ethyl acetate to provide 1.89 g (85%) of 8.

EXAMPLE 10

Two grams of the triflate analog of 20 were reacted as in the foregoing example with 134 mg P(tBu)₃, 433 mg of Pd(acac)₂, 375 mg of ZnF₂and 1.58 g of 5 to provide 1.56 g (90% yield) of 8.

Example 11

Piperidinol 25 is reacted with chlorodiphenylmethane as described in Fujii et al. Arzneim.-Forsch. 44, 527-538 (1994) to provide 6.

PATENT

WO/2023/213182CAREBASTINE SALT AND USE THEREOF

WIPO – Search International and National Patent Collections

Example 1: Potassium 2-(4-(4-(4-(diphenylmethoxy)piperidin-1-yl)butyryl)phenyl)-2-methylpropionate (carristin potassium salt ) preparation

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Step 1: Preparation of methyl 2-(4-(4-(4-(diphenylmethoxy)piperidin-1-yl)butyryl)phenyl)-2-methylpropionate

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Add 4-(diphenylmethoxy)piperidine hydrochloride (473mg, 1.77mmol), DMAC (4.5ml), K ₃ PO ₄ (1.13g, 5.3mmol), KI (29mg, 0.177mmol) to a 25ml single-neck bottle. , stir and heat to 100°C. Weigh 2-[4-(4-chloro-1-butyryl)phenyl]-2-methylpropionate methyl ester (600mg, 2.12mmol) and dissolve it in 1ml of DMAC. Add the reaction solution slowly and dropwise, and keep the reaction for 4~ 6h, TLC detects that the raw material reaction is complete. Cool to room temperature, add isopropyl acetate and water, and stir to separate layers. The aqueous phase was then extracted with isopropyl acetate, the organic phases were combined, washed twice with water, dried over anhydrous sodium sulfate, filtered, concentrated, and passed through a silica gel column to obtain 500 mg of the title product, yield 45%, purity: 97.3%.

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ESI-MS: m/z = 514.3(M+H) ⁺。

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¹H NMR (400 MHz， CDCl ₃) δ: 7.93 (d， J=8.3Hz， 2H)， 7.47 (m， 4H)， 7.42 (d， J=8.3Hz， 2H)， 7.30 (m， 4H)， 7.18 (m， 2H)， 3.64 (s， 3H)，2.98 (m， 4H)， 2.42 – 2.40 (m， 4H)， 1.96 (m， 4H)， 1.62 (s， 6H)， 1.42 (m， 4H)。

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Step 2: Preparation of 2-(4-(4-(4-(Diphenylmethoxy)piperidin-1-yl)butyryl)phenyl)-2-methylpropionic acid (carristin)

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Add (5-methyl-2-oxo-1,3-dioxo-4-yl)methyl-2-(4-(4-(4-(diphenylmethoxy))piperidine-1 to a 25ml three-necked flask) -Methyl)-butyryl)phenyl)-2-methylpropionate (320 mg, 0.62 mmol), 1.5 ml of methanol, 2 ml of 10% NaOH, heated to 60°C for 2 hours, and the TLC raw material reaction was completed. After the reaction is completed, cool to room temperature, concentrate to dryness, add EA, add hydrochloric acid to adjust the pH to 2~3, layer the layers, wash once with water, dry the organic phase, and concentrate to dryness to obtain 300 mg of the title product. Yield: 95%, purity 95.0%.

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ESI-MS: m/z = 500.3(M+H) ⁺。

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¹H NMR (400 MHz， CDCl ₃) δ:7.75-7.63 (m， 2H)， 7.57–7.24 (m，12H)， 5.48 (s，1H)，3.73 (m， 1H)， 3.05–3.02 (m， 2H)， 2.77–2.66 (m， 6H)， 2.20–2.07 (m， 2H)， 2.00–1.81 (m，4H)， 1.58 (s， 6H)。

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Step 3: Potassium 2-(4-(4-(4-(Diphenylmethoxy)piperidin-1-yl)butyryl)phenyl)-2-methylpropionate (Carristine Potassium Salt) Preparation

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Add 2-(4-(4-(4-(diphenylmethoxy)piperidin-1-yl)butyryl)phenyl)-2-methylpropionic acid (499mg, 1mmol) and acetonitrile 3.5 to a 25ml three-necked flask. ml, heated to 60°C, added potassium hydroxide (56 mg, 1 mmol), stirred, cooled down, a white solid precipitated, filtered, and dried to obtain 500 mg of carristine potassium salt, with a yield of 90% and a purity of 98.67%.

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ESI-MS: m/z = 500.3(M+H) ⁺。

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Example 2: Sodium 2-(4-(4-(4-(diphenylmethoxy)piperidin-1-yl)butyryl)phenyl)-2-methylpropionate (carristine sodium salt ) preparation

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In this example, the preparation method of 2-(4-(4-(4-(diphenylmethoxy)piperidin-1-yl)butyryl)phenyl)-2-methylpropionic acid is the same as in Example 1.

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Add 2-(4-(4-(4-(diphenylmethoxy)piperidin-1-yl)butyryl)phenyl)-2-methylpropionic acid (499mg, 1mmol) and acetonitrile 3.5 to a 25ml three-necked flask. ml, heated to 60°C, added sodium hydroxide (40 mg, 1 mmol) and stirred for 1 hour, concentrated to dryness, added methyl tert-butyl ether and stirred, filtered, and dried to obtain 458 mg of carristin sodium salt, yield 85%, purity 96.98 %.

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ESI-MS: m/z = 500.3(M+H) ⁺。

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