tert-butyl N-(1-oxo-1-phenylpropan-2-yl)carbamate

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

Procedure: tert-butyl 1-oxo-1-phenylpropan-2-ylcarbamate (40) (1.3 g, 5.0 mmol, 1.0 equiv.) was added to a 100 mL RBF followed by EtOH (39 mL). Next, a 37% solution of formaldehyde (8.1 mL, 100 mmol, 20.0 equiv.) was added to the reaction mixture and the solution heated to 35° C. Finally, a 0.5 M solution of K2CO3 (350 mg, 2.5 mmol, 5.0 mL dH2O, 0.5 equiv.) was added to the reaction flask and the solution stirred vigorously for 24 h. The solution was neutralized with 1% HCl, transferred to a separatory funnel with a 1.7 M solution of NaCl (5.0 g, 85.0 mmol, 50 mL H2O), and extracted with CH2Cl2 (5×50 mL). The organic layers were combined and dried over Na2SO4. The resulting solution was concentrated on a rotary evaporator and dried under vacuum to give a crude oil. The residue was purified by flash column chromatography (30% EtOAc/Hexanes) to give 1.1 g (79%) of 41 as a colorless oil. Rf=0.29 (50% EtOAc/Hexanes); IR (film) 3352, 2977, 1684, 1367, 1166 cm−1; 1H NMR (500 MHz, CDCl3) δ Major Rotamer: 8.00 (br s, 2H, Ph-H), 7.42 (br s, 3H, Ph-H), 5.87 (br s, 1H, carbamate-NH), 5.49 (br s, 1H, Boc-NH—CH), 4.12 (m, 2H, C—CH2), 3.76 (m, 2H, C—CH2), 3.32 (br s, 2H, CH2—OH), 1.63 (s, 3H, C—CH3), 1.26 (s, 9H, t-butyl-CH3). Minor Rotamer: 8.15 (br s, 2H, Ph-H), 7.51 (br s, 3H, Ph-H), 5.82 (br s, 1H, carbamate-NH), 3.09 (br s, 2H, CH2—OH), 1.09 (s, 9H, t-butyl-CH3); 13C NMR (125 MHz, CDCl3) Major Rotamer: δ 202.8, 155.1, 132.9, 128.5, 128.3, 80.5, 67.9, 64.4, 28.2, 21.6; LRMS (ESI-MS m/z): Mass calcd for C15H21NNaO4 [M+Na]+, 302.32. Found 302. extracted with CH2Cl2 (5×50 mL) dried over Na2SO4 The resulting solution was concentrated on a rotary evaporator dried under vacuum to give a crude oil The residue was purified by flash column chromatography (30% EtOAc/Hexanes)

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

Procedure: tert-butyl 1-(N-methoxy-N-methylcarbamoyl)ethylcarbamate (39) (2.3 g, 10.0 mmol, 1.0 equiv.) was added to a 250 mL RBF followed by THF (100 mL). The mixture was cooled to 0° C. via an ice bath and a 1.0 M solution of PhMgBr in THF (30.0 mL, 30.0 mmol, 3.0 equiv.) was added over 8 min. The reaction stirred for 1.0 h at 0° C. and the ice bath was removed. The reaction stirred for an additional 1.0 h at rt. and was again cooled to 0° C. via an ice bath. Next, the reaction was quenched by addition of 1.0 M HCl (60 mL). The solution was transferred to a separatory funnel with additional 1.0 M HCl (40 mL) and extracted with EtOAc (3×75 mL). The organic layers were combined, washed with sat. NaCl (1×50 mL), and dried over Na2SO4. The solution was then concentrated on a rotary evaporator and dried under vacuum to give 3.1 g of crude material. The residue was purified by flash column chromatography (15% EtOAc/Hexanes) to give 2.2 g (86%) of 40 as a colorless oil.10 Rf=0.25 (15% EtOAc/Hexanes); IR (film) 3356, 2977, 1680, 1164 cm−1; 1H NMR (500 MHz, CDCl3) δ 7.96 (d, J=7.5 Hz, 2H, Ph-H), 7.59 (t, J=7.5 Hz, 1H, Ph-H), 7.48 (t, J=7.5 Hz, 2H, Ph-H), 5.62 (br d, J=6.5 Hz, 1H, carbamate-NH), 5.30 (t, 1H, Boc-NH—CH), 3.78 (s, 3H, N—OCH3), 3.19 (s, 3H, N—CH3), 1.46 (s, 9H, Boc-t-butyl-CH3, 1.40 (d, J=7.0 Hz, 3H, CH—CH3); 13C NMR (125 MHz, CDCl3) δ 199.6, 155.5, 134.3, 133.9, 129.0, 128.8, 80.0, 51.3, 28.6, 20.1; LRMS (ESI-MS m/z): Mass calcd for C14H19NO3 [2M]+, 498.62. Found 499. Spectroscopic data were consistent with the literature data for this compound. the ice bath was removed The reaction stirred for an additional 1.0 h at rt and was again cooled to 0° C. via an ice bath Next, the reaction was quenched by addition of 1.0 M HCl (60 mL) The solution was transferred to a separatory funnel with additional 1.0 M HCl (40 mL) extracted with EtOAc (3×75 mL) washed with sat. NaCl (1×50 mL) dried over Na2SO4 The solution was then concentrated on a rotary evaporator dried under vacuum to give 3.1 g of crude material The residue was purified by flash column chromatography (15% EtOAc/Hexanes)

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

Procedure: tert-butyl 1-oxo-1-phenylpropan-2-ylcarbamate (40) (1.3 g, 5.0 mmol, 1.0 equiv.) was added to a 100 mL RBF followed by EtOH (39 mL). Next, a 37% solution of formaldehyde (8.1 mL, 100 mmol, 20.0 equiv.) was added to the reaction mixture and the solution heated to 35° C. Finally, a 0.5 M solution of K2CO3 (350 mg, 2.5 mmol, 5.0 mL dH2O, 0.5 equiv.) was added to the reaction flask and the solution stirred vigorously for 24 h. The solution was neutralized with 1% HCl, transferred to a separatory funnel with a 1.7 M solution of NaCl (5.0 g, 85.0 mmol, 50 mL H2O), and extracted with CH2Cl2 (5×50 mL). The organic layers were combined and dried over Na2SO4. The resulting solution was concentrated on a rotary evaporator and dried under vacuum to give a crude oil. The residue was purified by flash column chromatography (30% EtOAc/Hexanes) to give 1.1 g (79%) of 41 as a colorless oil. Rf=0.29 (50% EtOAc/Hexanes); IR (film) 3352, 2977, 1684, 1367, 1166 cm−1; 1H NMR (500 MHz, CDCl3) δ Major Rotamer: 8.00 (br s, 2H, Ph-H), 7.42 (br s, 3H, Ph-H), 5.87 (br s, 1H, carbamate-NH), 5.49 (br s, 1H, Boc-NH—CH), 4.12 (m, 2H, C—CH2), 3.76 (m, 2H, C—CH2), 3.32 (br s, 2H, CH2—OH), 1.63 (s, 3H, C—CH3), 1.26 (s, 9H, t-butyl-CH3). Minor Rotamer: 8.15 (br s, 2H, Ph-H), 7.51 (br s, 3H, Ph-H), 5.82 (br s, 1H, carbamate-NH), 3.09 (br s, 2H, CH2—OH), 1.09 (s, 9H, t-butyl-CH3); 13C NMR (125 MHz, CDCl3) Major Rotamer: δ 202.8, 155.1, 132.9, 128.5, 128.3, 80.5, 67.9, 64.4, 28.2, 21.6; LRMS (ESI-MS m/z): Mass calcd for C15H21NNaO4 [M+Na]+, 302.32. Found 302. extracted with CH2Cl2 (5×50 mL) dried over Na2SO4 The resulting solution was concentrated on a rotary evaporator dried under vacuum to give a crude oil The residue was purified by flash column chromatography (30% EtOAc/Hexanes)

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

Procedure: tert-butyl 1-(N-methoxy-N-methylcarbamoyl)ethylcarbamate (39) (2.3 g, 10.0 mmol, 1.0 equiv.) was added to a 250 mL RBF followed by THF (100 mL). The mixture was cooled to 0° C. via an ice bath and a 1.0 M solution of PhMgBr in THF (30.0 mL, 30.0 mmol, 3.0 equiv.) was added over 8 min. The reaction stirred for 1.0 h at 0° C. and the ice bath was removed. The reaction stirred for an additional 1.0 h at rt. and was again cooled to 0° C. via an ice bath. Next, the reaction was quenched by addition of 1.0 M HCl (60 mL). The solution was transferred to a separatory funnel with additional 1.0 M HCl (40 mL) and extracted with EtOAc (3×75 mL). The organic layers were combined, washed with sat. NaCl (1×50 mL), and dried over Na2SO4. The solution was then concentrated on a rotary evaporator and dried under vacuum to give 3.1 g of crude material. The residue was purified by flash column chromatography (15% EtOAc/Hexanes) to give 2.2 g (86%) of 40 as a colorless oil.10 Rf=0.25 (15% EtOAc/Hexanes); IR (film) 3356, 2977, 1680, 1164 cm−1; 1H NMR (500 MHz, CDCl3) δ 7.96 (d, J=7.5 Hz, 2H, Ph-H), 7.59 (t, J=7.5 Hz, 1H, Ph-H), 7.48 (t, J=7.5 Hz, 2H, Ph-H), 5.62 (br d, J=6.5 Hz, 1H, carbamate-NH), 5.30 (t, 1H, Boc-NH—CH), 3.78 (s, 3H, N—OCH3), 3.19 (s, 3H, N—CH3), 1.46 (s, 9H, Boc-t-butyl-CH3), 1.40 (d, J=7.0 Hz, 3H, CH—CH3); 13C NMR (125 MHz, CDCl3) δ 199.6, 155.5, 134.3, 133.9, 129.0, 128.8, 80.0, 51.3, 28.6, 20.1; LRMS (ESI-MS m/z): Mass calcd for C14H19NO3 [2M]+, 498.62. Found 499. Spectroscopic data were consistent with the literature data for this compound. the ice bath was removed The reaction stirred for an additional 1.0 h at rt and was again cooled to 0° C. via an ice bath Next, the reaction was quenched by addition of 1.0 M HCl (60 mL) The solution was transferred to a separatory funnel with additional 1.0 M HCl (40 mL) extracted with EtOAc (3×75 mL) washed with sat. NaCl (1×50 mL) dried over Na2SO4 The solution was then concentrated on a rotary evaporator dried under vacuum to give 3.1 g of crude material The residue was purified by flash column chromatography (15% EtOAc/Hexanes)