Boc-O-methyl-L-tyrosine

White powder

To a solution of compound 10 (498 mg, 1.61 mmol) in THF/MeOH/H2O (3:1:1, 5 mL)was added LiOHH2O (142 mg, 3.22 mmol)at 0 C. After stirring at 0 C for 1 h, the organic solvents wereevaporated. Then the residue was treated with 15percent aqueous citricacid to adjust the pH to 3, and the whole was extracted with ethylacetate (35 mL). The combined organic layers were washed withbrine (5 mL), dried with anhydrous Na2SO4, and concentrated invacuo. The crude product was subjected to silica gel column chromatography(ethyl acetate/petroleumether: 2:1) to give compound21 (466 mg, 98percent) as a colorless oil. 1H NMR (300 MHz, CD3OD):d 7.13 (2H, d, J8.4 Hz), 6.82 (2H, d, J8.4 Hz), 4.31e4.29 (1H, m), 3.73 (3H, s), 3.08 (1H, dd, J13.8, 4.5 Hz), 2.85 (1H, dd, J13.5, 8.7 Hz), 1.38 (9H, s). 13C NMR (75 MHz, CD3OD): d 175.42, 159.95, 157.67, 131.27, 131.27, 130.37, 114.81, 114.81, 80.50, 56.37, 55.64, 37.86, 28.67, 28.67, 28.67.Intermediate 11 (8.5 g, 27.5 mmol) was dissolved in 200 mLMethanol and water (v / v 1: 1), Sodium hydroxide (4.4 g, 110 mmol) was added portionwise at room temperature, Stir overnight at room temperature. Add 10percent aqueous hydrochloric acid to adjust the pH value to about 5, 500mL methylene chloride extraction, the organic layer was washed once with 100mL saturated brine, Dried over anhydrous sodium sulfate, filtered and the solvent was evaporated under reduced pressure to give the desired product, Yield 95percent. The next reaction can be carried out without further purification.Intermediate 11 (8.5 g, 27.5 mmol) was dissolved in a mixed solution of 200 mL of methanol and water (v / v 1: 1), room temperatureSodium hydroxide (4.4 g, 110 mmol) was added in portions and stirred overnight at room temperature. Add 10percent aqueous hydrochloric acid to adjust the pH value to about 5, and extract with 500 mL of dichloromethane. The organic layer is washed once with 100 mL of saturated saline, dried over anhydrous sodium sulfate, filtered and the solvent is evaporated under reduced pressure to obtain the target product in 95percent yield. The next reaction can be carried out without further purification.A mixture of Boc-L-Tyr-OH (5.0 g, 17.8 mmol) in NaOH solution (4M, 10 mL) was treated with second portion of NaOHsolution (4 M, 2 mL) and then dimethyl sulfate (0.9 mL).The reaction temperature was controlled at 20-30 oC by acooling bath. The addition was repeated four times. The reaction was stirred for 2 h atroom temperature after completion of the addition of dimethyl sulfate. The solutionwas acidified with 1 M aq. HCl solution, and then extracted by EtOAc (2×100 mL).The combined organic extracts were washed with brine, dried over Na2SO4, filteredCO2BnNHBocMeOS9and evaporated, giving Boc-Tyr(OMe)-OH as a colorless oil (5.0 g, 95percent yield).N - tert-butoxycarbonyl - L - tyrosine added to acetone, completely dissolve, keep the reaction system 20 - 35 °C, batch by adding 6 equivalent of sodium hydroxide, after adding stirring 2 hours, maintaining the reaction system 0 - 20 °C, dropwise 3 equivalent of dimethyl sulfate, after adding the room temperature (20 - 30 °C) reaction overnight, water is added to a reaction system, in 40 - 50 °C between evaporating the acetone, acetone after removing, adding ethyl acetate and ice, citric acid solid is acidified to pH=2 - 3, layered, abandoned to the aqueous phase, the oil phase of the saturated salt water for washing three times, sodium sulfate drying 2 hours, filtering to remove sodium sulfate, evaporate most of the ethyl acetate, adding petroleum ether and stirring crystallization, to obtain N - tert butoxycarbonyl - O - methyl - L - tyrosine, yield 64percent. N - tert butoxycarbonyl - O - methyl - L - tyrosine soluble in acetone, maintaining the 10 - 25 °C, slow access after drying of hydrochloric acid gas, reaction 5 hours, insufflating hydrochloric acid gas, cooling to 0 - 10 °C, triethylamine for adjusting pH=7, separate out a large amount of white solid, filtered, and dried to obtain the O - methyl - L - tyrosine, purity 99.5percent, yield 66percent.

Molecular Weight:295.33
XLogP3:1.8
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:7
Exact Mass:295.14197277
Monoisotopic Mass:295.14197277
Topological Polar Surface Area:84.9
Heavy Atom Count:21
Complexity:356
Defined Atom Stereocenter Count:1
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes