WO2024126771A1

WO2024126771A1 - Process for preparing (z)-3-(2-(5-bromo-1h-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile

Info

Publication number: WO2024126771A1
Application number: PCT/EP2023/086010
Authority: WO
Inventors: Cécile BOUGERET; Daniel John FINNEMORE; Craig Aaron FISHER; Mahesh Jayantilal SANGANEE
Original assignee: Evexta Bio
Priority date: 2022-12-16
Filing date: 2023-12-15
Publication date: 2024-06-20

Abstract

The present invention relates to a process for preparing (Z)-3-(2-(5-bromo-1H-indol-3-yl)-2- cyanovinyl)-4-methoxybenzonitrile comprising reacting tert-butyl 5-bromo-3-(cyanomethyl)- 1H-indole-1-carboxylate, 3-formyl-4-methoxybenzonitrile, and sodium ethoxide solution.

Description

PROCESS FOR PREPARING (Z)-3-(2-(5-BROMO-lH-INDOL-3-YL)-2-CYANOVINYL)-

4-METH0XYBENZ0NITRILE

FIELD OF THE INVENTION

The present invention relates to the field of synthesis in organic and medicinal chemistry. More particularly, the present invention provides an improved process for preparing an anticancer agent, namely (Z)-3-(2-(5-bromo- lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile.

BACKGROUND OF THE INVENTION

Kinesins are a superfamily of motor proteins that have ATP enzyme activity. They are involved in the normal biological activities of various cells, including mitosis, meiosis, and intracellular vesicle transport. Kinesin family member 20A (KIF20A, also known as MKlp2) is located on chromosome 5q31.2 and plays an important role in the occurrence and development of tumors. Recently, several studies have demonstrated that KIF20A may play an important role in the development and progression of many different types of cancer, such as melanoma, breast cancer, nasopharyngeal cancer, pancreatic cancer, hepatocellular carcinoma, lung cancer, and colorectal cancer.

In past years, a class of indole derivatives as compounds targeting KIF20A (MKlp2) has been developed such as compounds described in the international patent application WO 2014/086964.

More particularly, WO 2014/086964 focusses on (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2- cyanovinyl)-4-methoxybenzonitrile (Example 38 of WO 2014/086964), for which it has been evaluated an efficient antitumor activity at a nanomolar efficiency on various human cancer cells, demonstrating thereby a strong interest to use this lead compound for treating a large panel of cancer including for instance acute myeloid leukemia, lymphoma, breast cancer, pancreatic cancer, lung cancer and colon cancer. (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2- cyanovinyl)-4-methoxybenzonitrile is obtained by reacting tert-butyl 5-bromo-3- (cyanomethyl)-lH-indole-l -carboxylate with sodium hydride dispersion (NaH) and, then adding 3-formyl-4-methoxybenzonitrile. However, this synthesis reaction using NaH does not meet the requirements of an industrial scale and safety. Indeed, (Z)-3-(2-(5-bromo-lH-indol-3- yl)-2-cyanovinyl)-4-methoxybenzonitrile is only obtained with 30% yield, and the use of NaH involves delayed reaction onset and exotherm, evolution of hydrogen gas, and potential contamination of the final product with mineral oil.

Therefore, there is a need to develop and provide process for the synthesis of (Z)-3-(2-(5- bromo-lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile suitable for industrial scale, including economical and safety objectives.

SUMMARY OF THE INVENTION

In this context, the inventors have developed new reactive conditions for preparing (Z)-3-(2- (5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile starting from tert-butyl 5- bromo-3-(cyanomethyl)-lH-indole-l-carboxylate and 3-formyl-4-methoxybenzonitrile. Unexpectedly, the inventors have shown that the replacement of sodium hydride dispersion with a more process-friendly reagent, namely sodium ethoxide solution, allows to obtain (Z)-

3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile with an improved yield of 74% and a high LCMS purity of 99.1%.

Accordingly, the present invention thus relates to a process for preparing (Z)-3-(2-(5-bromo- lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile comprising the steps of: a) reacting tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate and 3-formyl-

4-methoxybenzonitrile with sodium ethoxide solution; and b) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile.

Particularly, sodium ethoxide solution is a sodium ethoxide/ethanol solution, preferably at a concentration of 21% w/w.

In a particular embodiment, the step a) is reacted at a temperature ranging from 25 to 60 °C, preferably from 40 to 45 °C.

In a further particular embodiment, the step a) is reacted for a period from 1 to 3 hours, preferably about 2 hours.

In a preferred embodiment, the step a) is reacted at a temperature ranging from 40 to 45 °C for a period of about 2 hours. In a further preferred embodiment, sodium ethoxide solution, tert-butyl 5-bromo-3- (cyanomethyl)-lH-indole-l -carboxylate, and 3-formyl-4-methoxybenzonitrile are used at step a) in stoichiometric amount.

In a particular embodiment, the step b) comprises the following steps: bl) adding water to mixture of step a), b2) filtering the mixture, then washing and drying the crude material, b3) optionally purifying the crude material with a MEK solution, and b4) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4- methoxybenzonitrile .

DETAILED DESCRIPTION OF THE INVENTION

(Z)-3-(2-(5-bromo- lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile (compound (6)) having the following formula:

is an effective inhibitor of kinesin family member 20A (KIF20A, also known as MKlp2) , which can be used as a drug for treating, for instance, diseases or pathologies associated with dysregulation of KIF20A or its pathway, such as cancer.

The present invention provides a simple and safe process for preparing this compound with a high yield and a high purity, starting from tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l- carboxylate and 3-formyl-4-methoxybenzonitrile, with sodium ethoxide solution.

The present invention relates to a process for preparing (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2- cyanovinyl)-4-methoxybenzonitrile comprising the steps of: a) reacting tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate and 3-formyl- 4-methoxybenzonitrile with sodium ethoxide solution; and b) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile. Sodium ethoxide, also called sodium ethylate or sodium ethanolate, (CAS Number: 141-52-6) having the formula C2HsONa is a strong base, which can be dissolved in polar solvents such as methanol or ethanol. In a preferred embodiment sodium ethoxide is dissolved in ethanol to form sodium ethoxide/ethanol solution, preferably at a concentration of 21% w/w. It is understood that the sodium ethoxide/ethanol solution can be easily prepared by a skilled person or commercially purchased.

In a particular embodiment, the step a) is reacted at a temperature ranging from 25 to 60 °C, from 30 to 55 °C, from 35 to 50 °C, preferably from 40 to 45 °C.

In a further particular embodiment, the step a) is reacted for a period from 1 to 3 hours, from 1.5 to 2.5 hours, preferably for a period of about 2 hours.

As used herein, the term “about” will be understood by these skilled in the art and can vary to a certain extent according to the context in which it used. If some uses of this term are not clear for those skilled in the art depending on the context, “about” means plus or minus 30%, 20%, preferably plus or minus 10%, more preferably plus or minus 5% of the specific term.

In a preferred embodiment, the invention relates to a process for preparing (Z)-3-(2-(5-bromo- lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile comprising the steps of: a) reacting tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate and 3-formyl- 4-methoxybenzonitrile with sodium ethoxide/ethanol solution at a temperature ranging from 40 to 45 °C for a period of about 2 hours; and b) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile.

In a further particular embodiment, sodium ethoxide solution, tert-butyl 5-bromo-3- (cyanomethyl)-lH-indole-l -carboxylate, and 3-formyl-4-methoxybenzonitrile at step a) are used in stoichiometric amounts.

It is well understood that a skilled person in art, such as an organic chemist, knows the concept of stoichiometric amounts. For instance, it means that sodium ethoxide solution or sodium ethoxide/ethanol solution, tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate, and 3-formyl-4-methoxybenzonitrile reacts with about the same molar amount or with a molar ratio equal to about 1. For instance, each of sodium ethoxide/ethanol solution, tert-butyl 5-bromo-3- (cyanomethyl)-lH-indole-l -carboxylate and 3 -formyl-4- methoxybenzonitrile is used at 1.00- 1.05 equivalents relative to the others. Preferably, 1.00 equivalent of tert-butyl 5-bromo-3- (cyanomethyl)-lH-indole-l -carboxylate, 1.00 equivalent of sodium ethoxide/ethanol solution, and 1.02 equivalents of 3-formyl-4-methoxybenzonitrile are used in the step a) as defined herein.

Step b) of the process of the invention relating to the recovering of (Z)-3-(2-(5-bromo-lH- indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile can be easily performed by a skilled person including non-exhaustive steps of quenching, filtering, washing, purifying and drying steps.

For instance, step b) of the process of the invention may further comprise the following steps: bl) adding water to mixture of step a), b2) filtering the mixture, then washing and drying the crude material, b3) optionally purifying the crude material with a MEK solution, and b4) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4- methoxybenzonitrile .

In a preferred embodiment, the process of the invention comprises the steps of: a) reacting tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate and 3-formyl- 4-methoxybenzonitrile with sodium ethoxide/ethanol solution; and bl) adding water to mixture of step a), b2) filtering the mixture, then washing and drying the crude material, b3) optionally purifying the crude material with a MEK solution, and b4) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4- methoxybenzonitrile .

In a more preferred embodiment, the process of the invention comprises the steps of: a) reacting tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate and 3-formyl- 4-methoxybenzonitrile wit sodium ethoxide/ethanol solution, at a temperature ranging from 40 to 45 °C for a period of about 2 hours; and bl) adding water to mixture of step a), b2) filtering the mixture, then washing and drying the crude material, b3) optionally purifying the crude material with a MEK solution, and b4) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4- methoxybenzonitrile .

Starting materials tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l -carboxylate and 3-formyl- 4-methoxybenzonitrile can be prepared by a skilled person thanks to any known methods of synthesis including any chemical synthesis currently used in organic chemistry. These starting materials can even be commercially purchased (tert-butyl 5-bromo-3-(cyanomethyl)-lH- indole-1 -carboxylate, CAS Number: 1419874-03-5; and 3-formyl-4-methoxybenzonitrile, (CAS Number: 21962-53-8).

For instance, tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate and 3-formyl-4- methoxybenzonitrile can be prepared by procedures of synthesis disclosed by WO 2014/086964.

In a particular embodiment, tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate is prepared by a process comprising the following steps of:

- reacting 5-bromo-lH-indole-3-carbaldehyde with formamide, methanol, and sodium borohydride, then adding potassium cyanide and stirring the resulting mixture at a temperature ranging from 40 to 45 °C to yield 2-(5-bromo-lH-indol-3-yl)acetonitrile; and

- reacting 2-(5 -bromo- IH-indol- 3 -yl) acetonitrile with di-tert-butyl-dicarbonate and 4- dimethylaminopyridine with acetonitrile at room temperature; and

- recovering tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate.

In a particular embodiment, 3-formyl-4-methoxybenzonitrile is prepared by a process comprising the following steps of:

- reacting 4-fluoro-3-formylbenzonitrile with methanol, and sodium methoxide at room temperature to yield 3-formyl-4-methoxybenzonitrile; and

- recovering 3-formyl-4-methoxybenzonitrile.

Further aspects and advantages of the present invention will be described in the following examples, which should be regarded as illustrative and not limiting. EXAMPLES

The process for preparing preparing (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4- methoxybenzonitrile is reproduced by Scheme 1 below.

Scheme 1:

1. Synthesis of tert-butyl 5-bromo-3-(cvanomethyl)-lH-indole-l-carboxylate (3)

1.1. Synthesis of 2-(5-bromo-lH-indol-3-yl)acetonitrile (2)

To a solution of 5-bromo-lH-indole-3-carbaldehyde (1 eq.) (1) in methanol: formamide (7:1) was added sodium borohydride at 0-10 °C. Then, the reaction mixture was stirred at room temperature for 30 minutes and potassium cyanide (2.5 eq.) was added. The mixture was stirred at 40 to 45 °C for 12 hours, then quenched with water. The crude residue was filtered, washed with EtOEfcEhO (1:1) and dried to afford 2-(5-bromo-lH-indol-3-yl)acetonitrile (2) with 57% yield.

1.2. Synthesis of tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate (3)

To a solution of di-tert-butyl-dicarbonate (1.1 eq.) and dimethylaminopyridine (0.05 eq.) in acetonitrile was added 2-(5-bromo-lH-indol-3-yl)acetonitrile (2) (1 eq.) at room temperature. Then, the reaction mixture was stirred at room temperature for 1 hour, then quenched with water. The crude residue was filtered, washed with heptane and dried to afford tert-butyl 5- bromo-3-(cyanomethyl)-lH-indole-l-carboxylate (3) with 93% yield.

2. Synthesis of 3-formyl-4-methoxybenzonitrile (5)

To a solution of 4-fluoro-3-formylbenzonitrile (4) (1 eq.) in methanol was added 5.4 M sodium methoxide/methanol solution (1.05 eq.) at 0-10 °C. Then, the reaction mixture was stirred at room temperature for 1.5 hour, and quenched with water. The crude residue was filtered, washed with heptane and dried to afford 3-formyl-4-methoxybenzonitrile (5) with 69% yield.

3. Synthesis of (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cvanovinyl)-4-methoxybenzonitrile

(6) (process according to the invention)

To a solution of tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l -carboxylate (3) (leq.) and formyl-4-methoxybenzonitrile (5) (1.02 eq.) in Ethanol was added sodium ethoxide/ethanol solution (1.00 eq.) at room temperature. Then, the reaction mixture was stirred at 40 to 45 °C for 2 hours, and quenched with water. The crude residue was filtered, washed with Ethanol, and dried. Material was added to Methyl Ethyl Ketone solution (MEK) and temperature was adjusted to 70-75 °C. Then, MEK solution was clarified by filtration. Filtrates were concentrated and the solid was then dried to afford (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2- cyanovinyl)-4-methoxybenzonitrile with 74% yield.

APCI-MS: (M-H) = 376

NMR (300 MHz, DMSO-d₆) 5 ppm: 11.99 (s, 1H), 8.22 (s, 1H), 8.08 (s, 1H), 7.91 (s, 2H), 7.70 (s, 1H), 7.60 - 7.15 (m, 3H), 3.97 (s, 3H).

LCMS purity: 99.1%

4. Synthesis of (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cvanovinyl)-4-methoxybenzonitrile

To a solution of tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate (3) (leq.) in THF was added sodium hydride (1.5 eq.) under an argon atmosphere at 0-5 °C. Then, 3-formyl- 4-methoxybenzonitrile (5) (1.2 eq.) was added in portions and the reaction mixture was stirred at room temperature for 1.5 hour. The reaction mixture was diluted with water. The resulting solid was filtered, washed successively with water, CH2Q2, DIPE and acetonitrile and dried in vacuo to afford (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile with 30% yield.

Claims

1. A process for preparing (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4- methoxybenzonitrile comprising the steps of: a) reacting tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate and 3-formyl- 4-methoxybenzonitrile with sodium ethoxide solution; and b) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4-methoxybenzonitrile.

2. The process according to claim 1, wherein sodium ethoxide solution is a sodium ethoxide/ethanol solution, preferably at a concentration of 21% w/w.

3. The process according to claim 1 or 2, wherein step a) is reacted at a temperature ranging from 25 to 60 °C.

4. The process according to any one of claims 1 to 3, wherein step a) is reacted at a temperature ranging from 40 to 45 °C.

5. The process according to any one of claims 1 to 4, wherein step a) is reacted for a period from 1 to 3 hours.

6. The process according to any one of claims 1 to 5, wherein step a) is reacted for a period of about 2 hours.

7. The process according to any one of claims 1 to 6, wherein step a) is reacted at a temperature ranging from 40 to 45 °C for a period of about 2 hours.

8. The process according to any one of claims 1 to 7, wherein sodium ethoxide solution, tertbutyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate, and 3-formyl-4- methoxybenzonitrile at step a) are used in stoichiometric amounts.

9. The process according to any of claims 1 to 8, wherein step b) comprise the following steps: bl) adding water to mixture of step a), b2) filtering the mixture, then washing and drying the crude material, b3) optionally purifying the crude material with a MEK solution, and b4) recovering (Z)-3-(2-(5-bromo-lH-indol-3-yl)-2-cyanovinyl)-4- methoxybenzonitrile .

10. The process according to any one of claims 1 to 9, wherein tert-butyl 5-bromo-3- (cyanomethyl)-lH-indole-l -carboxylate is prepared by a process comprising the following steps of:

- recovering tert-butyl 5-bromo-3-(cyanomethyl)-lH-indole-l-carboxylate.

11. The process according to any one of claims 1 to 9, wherein 3-formyl-4-methoxybenzonitrile is prepared by a process comprising the following steps of:

- recovering 3-formyl-4-methoxybenzonitrile.