The Synthetic Routes of Bepotastine besilate

Bepotastine besilate is a synthetic compound commonly used in the treatment of glaucoma, a condition characterized by increased pressure in the eye that can lead to damage to the optic nerve and loss of vision.
The synthesis of bepotastine besilate involves several steps, and there are several different synthetic routes that can be used to produce this compound.

One of the most common synthetic routes for bepotastine besilate involves the reaction of (S)-3-[2-(dibromoacetyl)amino-5-(trifluoromethyl)-2,3-dihydro-1H-inden-1-yl]-N-(2-hydroxy-5-methylbenzyl)acetamide with (R)-2-(4-chlorophenyl)-4,5-dihydroimidazo[1,2-d][1,4]benzoxazepine-9-one.
This reaction sequence involves several steps, including the synthesis of the starting materials, the protection of functional groups, and the deprotection of the final product.

The synthesis of (S)-3-[2-(dibromoacetyl)amino-5-(trifluoromethyl)-2,3-dihydro-1H-inden-1-yl]-N-(2-hydroxy-5-methylbenzyl)acetamide typically involves the reaction of (S)-2-(dibromoacetylamino)-N-(2-hydroxy-5-methylbenzyl)acetamide with (trifluoromethyl)sulfonyl chloride in the presence of a solvent such as dichloromethane.
The product is then treated with sodium carbonate and the excess trifluoromethylsulfonyl chloride is removed by filtration.
The resulting product is then hydrolyzed using a strong acid such as hydrochloric acid, and the resulting amino acid is deprotected using a reducing agent such as lithium aluminum hydride (LiAlH4).

The synthesis of (R)-2-(4-chlorophenyl)-4,5-dihydroimidazo[1,2-d][1,4]benzoxazepine-9-one typically involves the reaction of 4-chloro-2-(4-methoxyphenyl)imidazo[1,2-d][1,4]benzoxazepine-9-one with sodium hydroxide in the presence of a solvent such as water.
The product is then treated with an aqueous solution of sodium hydrogen carbonate, and the resulting precipitate is filtered and dried to yield the desired product.

Once the desired starting materials have been synthesized, the reaction sequence involving the formation of bepotastine besilate can be carried out.
This typically involves the condensation of the two starting materials in the presence of a solvent such as dimethylformamide, followed by the deprotection of the final product using a reducing agent such as lithium aluminum hydride (LiAlH4).

Overall, the synthesis of bepotastine besilate involves several steps, including the synthesis of the starting materials, the protection of functional groups, and the deprotection of the final product.
There are several different synthetic routes that can be used to produce this compound, and the choice of route will depend on factors such as the availability of starting materials, the cost of the synthesis, and the desired yield of the final product.