Some common heterocyclic compound, 70627-52-0, name is N-(4-(Benzyloxy)benzylidene)-4-fluoroaniline, molecular formula is C20H16FNO, 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. Application In Synthesis of N-(4-(Benzyloxy)benzylidene)-4-fluoroaniline
Step 1): To a solution of (S)-4-phenyl-2-oxazolidinone (41 g, 0.25 mol) in CH2Cl2 (200 mL), was added 4-dimethylaminopyridine (2.5 g, 0.02 mol) and triethylamine (84.7 mL, 0.61 mol) and the reaction mixture was cooled to 0 C. Methyl-4-(chloroformyl)butyrate (50 g, 0.3 mol) was added as a solution in CH2Cl2 (375 mL) dropwise over 1 h, and the reaction was allowed to warm to 22 C. After 17 h, water and H2SO4 (2N, 100 mL), was added the layers were separated, and the organic layer was washed sequentially with NaOH (10%), NaCl (sat’d) and water. The organic layer was dried over MgSO4 and concentrated to obtain a semicrystalline product. Step 2): To a solution of TiCl4 (18.2 mL, 0.165 mol) in CH2Cl2 (600 mL) at 0 C., was added titanium isopropoxide (16.5 mL, 0.055 mol). After 15 min, the product of Step 1 (49.0 g, 0.17 mol) was added as a solution in CH2Cl2 (100 mL). After 5 min., diisopropylethylamine (DIPEA) (65.2 mL, 0.37 mol) was added and the reaction mixture was stirred at 0 C. for 1 h, the reaction mixture was cooled to -20 C., and 4-benzyloxybenzylidine(4-fluoro)aniline (114.3 g, 0.37 mol) was added as a solid. The reaction mixture was stirred vigorously for 4 h at -20 C., then acetic acid was added as a solution in CH2Cl2 dropwise over 15 min, the reaction mixture was allowed to warm to 0 C., and H2SO4 (2N) was added. The reaction mixture was stirred an additional 1 h, the layers were separated, washed with water, separated and the organic layer was dried. The crude product was crystallized from ethanol/water to obtain the pure intermediate. Step 3): To a solution of the product of Step 2 (8.9 g, 14.9 mmol) in toluene (100 mL) at 50 C., was added N,O-bis(trimethylsilyl)acetamide (BSA) (7.50 mL, 30.3 mmol). After 0.5 h, solid TBAF (0.39 g, 1.5 mmol) was added and the reaction mixture stirred at 50 C. for an additional 3 h. The reaction mixture was cooled to 22 C., CH3OH (10 mL), was added. The reaction mixture was washed with HCl (1 N), NaHCO3 (1 N) and NaCl (sat’d.), and the organic layer was dried over MgSO4. Step 4): To a solution of the product of Step 3 (0.94 g, 2.2 mmol) in CH3OH (3 mL), was added water (1 mL) and LiOH.H2O (102 mg, 2.4 mmole). The reaction mixture was stirred at 22 C. for 1 h and then additional LiOH.H2O (54 mg, 1.3 mmole) was added. After a total of 2 h, HCl (1 N) and EtOAc was added, the layers were separated, the organic layer was dried and concentrated in vacuo. To a solution of the resultant product (0.91 g, 2.2 mmol) in CH2Cl2 at 22 C., was added ClCOCOCl (0.29 mL, 3.3 mmol) and the mixture stirred for 16 h. The solvent was removed in vacuo. Step 5): To an efficiently stirred suspension of 4-fluorophenylzinc chloride (4.4 mmol) prepared from 4-fluorophenylmagnesium bromide (1 M in THF, 4.4 mL, 4.4 mmol) and ZnCl2 (0.6 g, 4.4 mmol) at 4 C., was added tetrakis(triphenyl-phosphine)palladium (0.25 g, 0.21 mmol) followed by the product of Step 4 (0.94 g, 2.2 mmol) as a solution in THF (2 mL). The reaction was stirred for 1 h at 0 C. and then for 0.5 h at 22 C. HCl (1 N, 5 mL) was added and the mixture was extracted with EtOAc. The organic layer was concentrated to an oil and purified by silica gel chromatography to obtain 1-(4-fluorophenyl)-4(S)-(4-hydroxyphenyl)-3(R)-(3-oxo-3-phenylpropyl)-2-azetidinone: HRMS calc’d for C24H19F2NO3=408.1429, found 408.1411.
These compound has a wide range of applications. It is believed that with the continuous development of the source of the synthetic route 70627-52-0, its application will become more common.
Reference:
Patent; Veltri, Enrico P.; US2006/69080; (2006); A1;,
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