MethylN-(p-Toluenesulfonyl)carbamate

[14437-03-7] C9H11NO4S (MW 229.25) InChI = 1S/C9H11NO4S/c1-7-3-5-8(6-4-7)15(12,13)10-9(11)14-2/h3-6H,1-2H3,(H,10,11) InChIKey = KNVDHKOSDVFZTO-UHFFFAOYSA-N (reagent used to introduce a protected amino group) Physical Data: 1 mp 111–113 °C (lit. 115 °C,2a 108–111 °C2b), after recrystallization from CCl4. Solubility: soluble in DMSO, MeOH, THF, AcOEt, CHCl3, CH2Cl2; insoluble in H2O. Analysis of Reagent Purity: NMR data3 for the reagent: 1H-NMR (CDCl3): δ2.45 (3H, s), 3.71 (s, 3H), 7.35 (d, J = 8 Hz, 2H), 7.93 (d, J = 8 Hz, 2H), 7.40–7.65 (br s, 1H); 13C-NMR (DMSO-d6): δ 21.4, 53.2, 127.8, 129.9, 136.7, 144.6, 152.0. Preparative Methods: prepared from commercially available p-toluenesulfonamide. Method A:3 Methyl chloroformate (4.43 mL, 0.060 mol) was slowly added to a solution of p-toluenesulfonamide (6.48 g, 0.040 mol) and Et3N (10.12 g, 0.100 mol) in anhydrous CH3CN (40 mL). The resulting solution was stirred at room temperature for 6 h and the solvent was evaporated in vacuo. The residue was dissolved in EtOAc and aq NaHCO3 was added. The water layer was separated and acidified with a mixture of ice and conc HCl to give an oily precipitate that slowly crystallized upon standing. The crystals were collected by filtration, washed with water, and dried to give the reagent (4.09 g, 45% yield, 107–108 °C). Method B:4 To a suspension of p-toluenesulfonamide (24.3 g, 0.14 mol) in MeOH (30 ml), NaOMe (30 wt. % in MeOH, 37.9 g) was added, and the mixture was stirred at room temperature. p-Toluenesulfonamide was dissolved exothermically to give the sodium salt. After the addition of dimethylcarbonate (15.2 g, 0.17 mol), the mixture was refluxed for 18 h. The volatiles and excess dimethylcarbonate were evaporated. The residue was dissolved in water and the solvent was adjusted to pH 2 with conc HCl (23 g). The resulting precipitate was filtrated to give the reagent (30.9 g, 95% yield). Method C:5 To a solution of N-chloro-p-toluenesulfonamidate potassium (1.9 g, 7.7 mmol) in CH3CN (10 ml), Pd(PhCN)2Cl2 (120 mg) and MeOH (0.27 g, 8.5 mmol) were added and stirred at 25 °C for 3 h under CO (g) (initial pressure 4.2 MPa). After the CO (g) consumption has stopped, the volatiles were evaporated. The solid residue was recrystallized to give the reagent (1.42 g, 80% yield).