Boc-L-methionine

white to off-white microcrystalline powder

7.2 g Methionine was dissolved in a mixture of 50 mL water and 50 mL acetonitrile. To this solution was added2 g NaOH (0.05 mol). The obtained mixture was cooled down to 0°C and then 10.9 g di-t-butyl dicarbonate (0.05 mol)was added. After addition, the mixture was warmed to room temperature (24-25°C) and reacted for 12 h. Acetonitrilewas removed by distillation. Potassium carbonate was added to the residue and the pH thereof was adjusted to 12. Afterextracted with 50 mL dichloromethane twice, the organic layers were discarded. To the aqueous layer was added 1 Ndilute hydrochloric acid to adjust the pH to 6. After extracted with 50 mL dichloromethane twice, the organic layers werecollected together and washed with 50 mL saturate solution of sodium chloride and then dried over anhydrous sodiumsulfate, followed by concentration to obtain a viscous product (11.4 g). The yield was 95percent.1H NMR (500 MHz, CDCl3) δ 11.62 (br, 1 H), 6.91 (br, 1 H), 4.40 (m. 1H), 2.52 (t, J = 4.8 Hz, 2 H), 2.05 (s, 3H), 1.92∼2.15(m. 2 H), 1.42 (s, 9 H). Ms (M++1): 250.To the solution of L-methionine (43) (2 g, 13.40 mmol) in water (12 mL) and acetonitrile (12 mL) was added NaOH (0.804 g, 20.11 mmol) and boc-anhydride (4.67 mL, 20.11 mmol) at 0 °C. The reaction mixture was stirred at room temperature for 12h. After completion, reaction mixture was concentrated under vacuum to remove acetonitrile and the remaining acqueous layer was diluted with 50 mL water. Aqueous layer was washed with ethylacetate (2 x 50 mL). The aqueous phase was then adjusted to pH ~ 4-5 using aqueous 1N HCl solution and extracted with dichloromethane (4 x 50 mL). Combined organic extracts were washed with brine (100 mL), dried over Sodium sulphate and evaporated under reduced pressure to yield (tert-butoxycarbonyl)-L-methionine (44) as a gummy compound (0.6 g, 8.02 mmol, 60 percent yield) 7.2 g Methionine was dissolved in a mixture of 50 mL water and 50 mL acetonitrile. To this solution was added 2 g NaOH (0.05 mol). The obtained mixture was cooled down to 0° C. and then 10.9 g di-t-butyl dicarbonate (0.05 mol) was added. After addition, the mixture was warmed to room temperature (24-25° C.) and reacted for 12 h. Acetonitrile was removed by distillation. Potassium carbonate was added to the residue and the pH thereof was adjusted to 12. After extracted with 50 mL dichloromethane twice, the organic layers were discarded. To the aqueous layer was added 1N dilute hydrochloric acid to adjust the pH to 6. After extracted with 50 mL dichloromethane twice, the organic layers were collected together and washed with 50 mL saturate solution of sodium chloride and then dried over anhydrous sodium sulfate, followed by concentration to obtain a viscous product (11.4 g). The yield was 95percent.

Used in biochemical reagents and peptide synthesis.

Molecular Weight:249.33
XLogP3:1.6
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:7
Exact Mass:249.10347926
Monoisotopic Mass:249.10347926
Topological Polar Surface Area:101
Heavy Atom Count:16
Complexity:250
Undefined Atom Stereocenter Count:1
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes