Some common heterocyclic compound, 349-43-9, name is Ethyl 2-fluoropropionate, molecular formula is C5H9FO2, traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route. 349-43-9
Syntheses of the Intermediate Sulfinamide Esters A3.3 and A3.4In a dry apparatus under an inert atmosphere a solution of diisopropylamine (3.35 g, 101 mmol) in tetrahydrofuran (25 ml) was treated with n-butyl lithium (1.6M in hexane, 20.7 ml). The solution was stirred at -7¡ã C. for 40 minutes. Thereafter, the solution was cooled to -75¡ã C. and a solution of ethyl 2-fluoropropanoate (3.98 g, 33.2 mmol) in tetrahydrofuran (5 ml) was added dropwise. After 40 minutes a solution of chlorotitanium triisopropoxide (8.64 g, 33.2 mmol) in tetrahydrofuran (15 ml) was slowly added dropwise. After 40 minutes at -72¡ã C. to the orange colored solution was added dropwise a solution of (R)-2-methyl-propane-2-sulfinic acid [1-(2-fluorophenyl)-(E)-ethylidene]-amide (intermediate A2.1) (4.0 g, 16.6 mmol) in tetrahydrofuran (5 ml). Stiffing was continued at -72¡ã C. for 4 hours, then the reaction mixture was kept at -20¡ã C. for 17 hours. For the workup, the reaction mixture was quenched with an aqueous solution of ammonium chloride (13percent, 100 ml). The precipitate formed was diluted with water and the resulting mixture extracted three times with ethyl acetate. The organic layers were washed with brine, then combined, dried and evaporated at reduced pressure. Purification of the crude product by chromatography on silica gel using a 5:2-mixture auf heptane and ethyl acetate as the eluent yielded a 1:2-mixture of the (2S,3R)-2-fluoro-3-(2-fluoro-phenyl)-2-methyl-3-((R)-2-methyl-propane-2-sulfinylamino)-butyric acid ethyl ester (A3.3) and (2R,3R)-2-Fluoro-3-(2-fluoro-phenyl)-2-methyl-3-((R)-2-methyl-propane-2-sulfinylamino)-butyric acid ethyl ester (A3.4) (4.43 g, 74percent) as a light yellow oil. MS (ISP): m/z=362.2 [M+H]+.
These compound has a wide range of applications. It is believed that with the continuous development of the source of the synthetic route 349-43-9, its application will become more common.
Reference:
Patent; Hilpert, Hans; Wostl, Wolfgang; US2012/258962; (2012); A1;,
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