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ChemicalBook CAS DataBase List Escitalopram oxalate
219861-08-2

Escitalopram oxalate synthesis

12synthesis methods
The synthesis of escitalopram was carried out in several different routes [30-33]. 5-Cyanophthalide (72) was treated with Grignard reagent 73 at 0°C to provide intermediate 75 which was reacted in situ with another Grignard reagent 76 to afford the diol in a one-pot process. Racemic diol 77 was resolved using (+)-p-toluoyltartaric acid to afford desired S isomer 78 in 55% yield. The ring closure reaction was carried out at 0°C using methanesulfonyl chloride in toluene to furnish escitalopram (7) in 60% yield.

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Yield:219861-08-2 98.57%

Reaction Conditions:

in acetone at 25 - 30;Industry scale;

Steps:

2

Preparation of Escitalopram OxalateThe residue obtained in Example 1 was dissolved in acetone (120 lit) at 25-30° C. A solution of oxalic acid dihydrate (17 Kg, 0.135 kmoles) in acetone (34 lit) was introduced over 30 minutes. The reaction mass was stirred for 2 hrs, cooled to 10° C. and further stirred for 1 hr. The solid obtained was isolated by filtration, washed with acetone (2×40 lit) and dried in a vacuum oven for 4-5 hrs at 50-55° C. to obtain the title compound.Yield: 40.0 Kg, 98.57%Chiral purity:->99.5%

References:

US2010/204493,2010,A1 Location in patent:Page/Page column 8

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