Process for the preparation of tavaborole

1. A process for the preparation of tavaborole, a compound of formula I, comprising:

a) reacting 2-halo-5-fluorotoluene, a compound of formula II

with a borate ester to obtain 2-methyl-4-fluorophenylboronic acid, a compound of formula III, wherein X is a halogen selected from chloro, bromo or iodo;

b) converting the compound of formula III to 2-halomethyl-4-fluorophenylboronic acid, a compound of formula IV

in the presence of mixture of halogenating agents; and

c) cyclizing the compound of formula IV to obtain tavaborole.

2. The process as claimed in claim 1 , wherein in step b) the mixture of halogenating agents is a mixture of brominating agents.

3. The process as claimed in claim 2 , wherein in step b) the mixture of brominating agents comprises bromine and N-bromosucciminide.

4. The process as claimed in claim 3 , wherein bromine is used in catalytic amount to the amount of N-bromosuccinimide.

5. The process as claimed in claim 1 , wherein in step b) halogenation is carried out in the presence of a radical initiator.

6. The process as claimed in claim 1 , further comprising isolating tavaborole from a mixture of water and an organic solvent selected from the group consisting of C 1-4 alcohols, ethers, amides, esters, nitriles, sulfoxides, ketones, hydrocarbons and halogenated hydrocarbons and mixtures thereof.

7. The process as claimed in claim 6 , wherein the isolating comprises:

a) dissolving tavaborole in a solvent selected from the group consisting of C 1-4 alcohols, ethers, amides, esters, nitriles, sulfoxides, ketones, hydrocarbons and halogenated hydrocarbons and mixtures thereof to obtain a solution;

b) adding water as an anti-solvent to the above solution; and

c) isolating tavaborole from the above step (b).

8. The process as claimed in claim 6 , wherein the isolation comprises isolating from a mixture of C 1-4 alcohol and water solvent.

9. The process as claimed in claim 8 , wherein a level of the compound of formula V and/or the level of compound of formula XIV

is less than 0.5% w/w with respect to the obtained tavaborole as determined by HPLC.

10. A method for preparing tavaborole, comprising the steps of:

(a) providing a batch of tavaborole or a salt thereof thereof prepared by the process as claimed in claim 1 ;

(b) assessing the purity of said batch of tavaborole, by using a compound of formula V or a compound of formula XIV as a reference marker to determine the level of the compound of formula V or the compound of formula XIV

and

(c) selecting the batch of tavaborole only if the % of the compound of formula V or the % of the compound of formula XIV is less than 0.15% w/w as determined by HPLC.

11. A method for preparing tavaborole thereof as prepared by the process as claimed in claim 1 , further comprising the steps of:

(a) providing a standard solution of compound V or compound XIV

(b) using the standard solution as a reference marker to determine a level of the compound of formula V or the compound of formula XIV in tavaborole.