N-(TERT-BUTOXYCARBONYL)-L-SERINE BETA-LACTONE

Conditions: temp:-45.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Methyl azodicarboxylate-derivatized resin (6.55 g, 4.0 meq) was swollen briefly (15 min) in dry THF (100 mL). The stirred suspension of beads was cooled to -45° C. and BOC-L-serine (473.5 mg, 2.30 mmol) was added. To this mixture at -45° C. was added a solution of triphenylphosphine (1.06 g, 4.0 mmol) in THF (5 mL) dropwise over 10 min. The suspension was stirred 30 min at -45° C., allowed to warm slowly to 0° C. over 1 h, and stirred 2 h further. H2O (36μL) was added as a precautionary quench and the resin was filtered and washed with THF (2 ×100 mL) and CH3CN (100 mL). The filtrate and washings were pooled and concentrated in vacuo at 35° C. The residue was flash chromatographed (35% EtOAc/hexane) to yield 242.7 mg (56%) of BOC-L-serine β-lactone: mp 119.5-120.5° C (dec); [α]25 -26.7 (±0.2)°(c 1.0, CH3CN); IR [Fluorolube (trademark) mull](CH2Cl2 cast) 3358 (s), 1836 (s), 1678 (vs), 1532 (s), 1291 (m), 1104 (s) cm-1 ; ε1847 cm-1 (0.1 mm KBr, THF or CH3CN) 0.34 mL mg-1 mm-1, 64 M-1 ; mm-1 ; 1H NMR (200 MHz, CD2Cl2) δ5.53 (br s, 1H, NH), 5.05 (dd, 1H, 8, 6 Hz, CH), 4.47 (~d, 2H, 6 Hz, CH2O), 1.47 (s, 9H, tert-Bu); 13C NMR (50.32 MHz, CD2Cl2) ≃170.0 (s), 155.1 (s), 81.5 (s), 66.6 (t), 59.9 (d), 28.2 (q); Anal. Calc. for C8H13NO4 : C, 51.33; H, 7.00; N, 7.48. Found: C, 51.04; H, 6.97; N, 7.42; EI--MS: 188.0929 (MH+, 188.0923 calcd.); CI--MS (NH3) 205 (M+NH+), 392 (2M+NH4+). The stirred suspension of beads to warm slowly to 0° C. over 1 h stirred 2 h further a precautionary quench the resin was filtered washed with THF (2 ×100 mL) and CH3CN (100 mL) concentrated in vacuo at 35° C chromatographed (35% EtOAc/hexane)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred mixture of 2 (1.34 mmol) and anhydrous p-toluenesulphonic acid (72 h under vacuum in the presence of P2O5) (1.43 mmol), kept at 0° C. under N2, trifluoroacetic acid (3 mL) was added dropwise in the course of 10 min. The solution was reacted under stirring at 0° C. for 15 min, allowed to reach room temperature, and concentrated at a temperature below 30° C. The oily residue was kept under vacuum for 1 h, and the resulting white solid triturated and washed with dry diethyl ether, then kept under vacuum for 24 h. Yield 81%. Mp and 1H NMR are in accordance with literature (Arnold, et al., 1988). kept at 0° C. under N2 The solution was reacted to reach room temperature concentrated at a temperature below 30° C The oily residue was kept under vacuum for 1 h the resulting white solid triturated washed with dry diethyl ether kept under vacuum for 24 h

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred mixture of 2 (1.34 mmol) and anhydrous p-toluenesulphonic acid (72 h under vacuum in the presence of P2O5) (1.43 mmol), kept at 0° C. under N2, trifluoroacetic acid (3 mL) was added dropwise in the course of 10 min. The solution was reacted under stirring at 0° C. for 15 min, allowed to reach room temperature, and concentrated at a temperature below 30° C. The oily residue was kept under vacuum for 1 h, and the resulting white solid triturated and washed with dry diethyl ether, then kept under vacuum for 24 h. Yield 81%. Mp and 1H NMR are in accordance with literature (Arnold, et al., 1988). kept at 0° C. under N2 The solution was reacted to reach room temperature concentrated at a temperature below 30° C The oily residue was kept under vacuum for 1 h the resulting white solid triturated washed with dry diethyl ether kept under vacuum for 24 h

Conditions: temp:-35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of dry PPh3 (72 h under vacuum in the presence of P2O5) (5 mmol) in dry CH3CN (31 mL), kept at −50° C. under N2, dimethylazodicarboxylate (5 mmol) and, after 20 min, a solution of 1 (4.47 mmol) in CH3CN (10.4 mL), were added dropwise. The mixture was stirred for 1.5 h at −50/−35° C. and concentrated. Purification of the residue by flash-chromatography (cyclohexane/EtOAc 8:2 to 6:4) gave crude 2, which was finally washed and triturated to afford a white solid. Mp 120-122° C. (Et2O). [α]D20=−27° (c 0.1, CH3CN). 1H NMR is in accordance with literature (Arnold, et al., 1985). 72 h kept at −50° C. under N2 concentrated Purification of the residue by flash-chromatography (cyclohexane/EtOAc 8:2 to 6:4) gave crude 2, which was finally washed triturated to afford a white solid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of m-anisidine (171 mg, 1.38 mmol) in THF (30 ml), N-(tert-butoxycarbonyl)-L-serine β-lactone (200 mg, 1.06 mmol) was added, and the mixture was refluxed overnight under argon. The reaction mixture was concentrated on a rotary evaporator. The residue was subjected to flash column chromatography, eluting with EtOAc/hexanes of various compositions. the mixture was refluxed overnight under argon The reaction mixture was concentrated on a rotary evaporator eluting with EtOAc/hexanes of various compositions

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: K2HPO4 (0.446 g, 3.28 mmol, dried 4 h at 130° C.) and 18-crown-6 ether (0.867 g, 3.28 mmol) were stirred 16 h in anhydrous DMF (10 mL). BOC-L-serine β-lactone (169 mg, 0.902 mmol) was deprotected to (S)-3-amino-2-oxetanone trifluoroacetic acid salt and added as a solution in DMF (3 mL). The mixture was stirred 3 days, diluted with H2O (to 50 mL), and applied to a column of AG1-X8 (trademark) (80 mL, 3 cm dia., OH- form). Elution (2 mL/min) with a linear gradient (0 to 3M over 10 L) of formic acid afforded O-phospho-L-serine 145.6 mg) in 87% yield after lyophilization: mp 170°-171° C. (dec) (lit. mp 175°-176° C. (dec)); [α]D 25 +7.2° (c 1.0, H2O) (lit. [α]D 25 +7.2° (c 1.0, H2O)); IR (KBr disk) 3420 (w, br), 3180 (w), 2700 (w), 2400-2260 (w), 1620 (w), 1560 (m), 1260 (m), 1089 (s), 1045 (s), 1000 (s), 970 (s), 740 (m), 810 (m) cm-1 ; 1H NMR (300 MHz, D2O+DC1)δ 4.37-4.27 (m, 2H, CH-CHH), 4.26-4.16 (m, 1H, CHH)31 ; 31p NMR (161.96 MHz, D2O+DC1) -0.45 (br (s). Anal. Calc. for C3H3NO6P: C, 19.47; H, 4.35; N, 7.57. Found: C, 19.27; H, 4.29; N, 7.82; POSFAB-MS (glycerol/HC1 ) 186 (MH+), 371 (M2H+); Rf 0.43 (System A). Elution (2 mL/min) with a linear gradient (0 to 3M over 10 L) of formic acid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: BOC-L-serine β-lactone (600. mg, 3.20 mmol) and anhydrous p-toluenesulfonic acid (579 mg, 3.36 mmol) were treated with distilled CF3COOH (10 mL) at 0°-5° C. for 10 min. Removal of solvent in vacuo as above provided a white crystalline residue which was triturated with dry Et2O (20 mL) and filtered to yield (S)-3-amino-2oxetanone p-toluene sulfonic acid salt (806 mg, 97%). This material was analytically pure; however, if desired, recrystallization could be effected from DMF/Et2O (25° C.→-20° C.): mp (~4° C./min) 135° C. (darkening), 173° C. (dec. rapid); [α]D25 -15.9 (±0.1)° (c 2.2, DMF); IR 3040 (s, vbr), 1838 (vs), 1600 (w), 1585 (w), 1550 (m) cm-1 ; IR (pH 6.8, aqueous solution) 1820 cm-1 ; IR (DMF solution) 1830 cm-1 ; 1H NMR (300 MHz, d7 -DMF)δ 7.66 (d, 2H, 8.0 Hz, o-ArH), 7.15 (d, 2H, 8.0 Hz, m-ArH), 5.53 (dd, 1H, 4.6, 6.5 Hz, CH), 4.74 (m, 1H, CHHO), 4.68 (m, 1H, CHHO), 3.70 (vbr s, 3H, NH3 +), 2.31 (s, 3H, ArCH3); 13C NMR (75.5 MHz, d7-DMF) δ 165.84, 145.12, 139.14, 128.67, 126.08, 64.70, 57.45, 20.70. Anal. Calc. for C10H13NO5S: C, 46.32; H, 5.05; N, 5.04; S, 12.37. Found: C, 46.44; H, 5.14; N, 5.24; S, 12.41; POSFAB-MS (glycerol) 88 (MH+ =C3H6NO2), 180 (MH+ (gly)), 260 (MH+ (TsOH)). The enantiomeric (R)- 3-amino-2-oxetanone salt was produced in an identical manner from BOC-D-serine β-lactone prepared from BOC-D-serine. Removal of solvent in vacuo as above provided a white crystalline residue which was triturated with dry Et2O (20 mL) filtered

Conditions: temp:-45.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Methyl azodicarboxylate-derivatized resin (6.55 g, 4.0 meq) was swollen briefly (15 min) in dry THF (100 mL). The stirred suspension of beads was cooled to -45° C. and BOC-L-serine (473.5 mg, 2.30 mmol) was added. To this mixture at -45° C. was added a solution of triphenylphosphine (1.06 g, 4.0 mmol) in THF (5 mL) dropwise over 10 min. The suspension was stirred 30 min at -45° C., allowed to warm slowly to 0° C. over 1 h, and stirred 2 h further. H2O (36μL) was added as a precautionary quench and the resin was filtered and washed with THF (2 ×100 mL) and CH3CN (100 mL). The filtrate and washings were pooled and concentrated in vacuo at 35° C. The residue was flash chromatographed (35% EtOAc/hexane) to yield 242.7 mg (56%) of BOC-L-serine β-lactone: mp 119.5-120.5° C (dec); [α]25 -26.7 (±0.2)°(c 1.0, CH3CN); IR [Fluorolube (trademark) mull](CH2Cl2 cast) 3358 (s), 1836 (s), 1678 (vs), 1532 (s), 1291 (m), 1104 (s) cm-1 ; ε1847 cm-1 (0.1 mm KBr, THF or CH3CN) 0.34 mL mg-1 mm-1, 64 M-1 ; mm-1 ; 1H NMR (200 MHz, CD2Cl2) δ5.53 (br s, 1H, NH), 5.05 (dd, 1H, 8, 6 Hz, CH), 4.47 (~d, 2H, 6 Hz, CH2O), 1.47 (s, 9H, tert-Bu); 13C NMR (50.32 MHz, CD2Cl2) ≃170.0 (s), 155.1 (s), 81.5 (s), 66.6 (t), 59.9 (d), 28.2 (q); Anal. Calc. for C8H13NO4 : C, 51.33; H, 7.00; N, 7.48. Found: C, 51.04; H, 6.97; N, 7.42; EI--MS: 188.0929 (MH+, 188.0923 calcd.); CI--MS (NH3) 205 (M+NH+), 392 (2M+NH4+). The stirred suspension of beads to warm slowly to 0° C. over 1 h stirred 2 h further a precautionary quench the resin was filtered washed with THF (2 ×100 mL) and CH3CN (100 mL) concentrated in vacuo at 35° C chromatographed (35% EtOAc/hexane)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred mixture of 2 (1.34 mmol) and anhydrous p-toluenesulphonic acid (72 h under vacuum in the presence of P2O5) (1.43 mmol), kept at 0° C. under N2, trifluoroacetic acid (3 mL) was added dropwise in the course of 10 min. The solution was reacted under stirring at 0° C. for 15 min, allowed to reach room temperature, and concentrated at a temperature below 30° C. The oily residue was kept under vacuum for 1 h, and the resulting white solid triturated and washed with dry diethyl ether, then kept under vacuum for 24 h. Yield 81%. Mp and 1H NMR are in accordance with literature (Arnold, et al., 1988). kept at 0° C. under N2 The solution was reacted to reach room temperature concentrated at a temperature below 30° C The oily residue was kept under vacuum for 1 h the resulting white solid triturated washed with dry diethyl ether kept under vacuum for 24 h

Conditions: temp:-35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of dry PPh3 (72 h under vacuum in the presence of P2O5) (5 mmol) in dry CH3CN (31 mL), kept at −50° C. under N2, dimethylazodicarboxylate (5 mmol) and, after 20 min, a solution of 1 (4.47 mmol) in CH3CN (10.4 mL), were added dropwise. The mixture was stirred for 1.5 h at −50/−35° C. and concentrated. Purification of the residue by flash-chromatography (cyclohexane/EtOAc 8:2 to 6:4) gave crude 2, which was finally washed and triturated to afford a white solid. Mp 120-122° C. (Et2O). [α]D20=−27° (c 0.1, CH3CN). 1H NMR is in accordance with literature (Arnold, et al., 1985). 72 h kept at −50° C. under N2 concentrated Purification of the residue by flash-chromatography (cyclohexane/EtOAc 8:2 to 6:4) gave crude 2, which was finally washed triturated to afford a white solid