methyl (2R)-2-(4-hydroxyphenyl)-2-[(2-methylpropan-2-yl)oxycarbonylamino]acetate

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

Procedure: A 0° C. solution of (R)-Methyl 2-(tert-butoxycarbonylamino)-2-(4-hydroxyphenyl)acetate (2.8 g, 10 mmol), (S)-2-methyl-1-butanol (1.1 mL, 10 mmol), triphenylphosphine (2.6 g, 10 mmol), and tetrahydrofuran (100 mL) was treated dropwise with diisopropylazodicarboxylate (1.9 mL, 10 mmol) via syringe. The resulting reaction mixture was allowed to warm to room temperature and maintained overnight. The reaction was concentrated and the residue was purified by column chromatography on silica gel (5%-10% ethyl acetate in hexanes) to afford (2R)-Methyl 2-(tert-butoxycarbonylamino)-(4-((S)-2-methyl-butoxy)-phenyl)acetate (2.8 g, 80% yield) as a clear, colorless oil: 1H NMR (400 MHz, CDCl3) δ 7.27 (d, J=7.3 Hz, 2H), 6.88 (d, J=8.6 Hz, 2H), 5.49 (d, J=6.6 Hz, 1H), 5.26 (d, J=7.3 Hz, 1H), 3.81 (dd, J=9.1, 6.1 Hz, 1H), 3.73 (s, 3H), 3.69-3.76 (m, 1H), 1.86 (dq, J=13.1, 6.5 Hz, 1H), 1.52-1.61 (m, 1H), 1.45 (s, 9H), 1.22-1.33 (m, 2H), 1.02 (d, J=6.8 Hz, 3H), 0.95 (t, J=7.5 Hz, 3H); LRMS (ESI) m/e 352.2 [(M+H)+, calcd for C19H30NO5 352.5]. The resulting reaction mixture maintained overnight The reaction was concentrated the residue was purified by column chromatography on silica gel (5%-10% ethyl acetate in hexanes)

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

Procedure: (R)-tert-Butoxycarbonylamino-(4-hydroxy-phenyl)-acetic acid methyl ester (10 mmol), Lithium Boron hydride (1.089 g, 50 mmol) and THF (50 ml) were combined and stirred at room temperature overnight. Ice (20 ml) was added into the reaction mixture with stirring. Saturated citric acid was then added dropwise until no more bubbles were generated. The reaction mixture was transferred to a separatory funnel. The aqueous layer was extracted with ethyl acetate (3×30 ml). The combined organic layers were washed with saturated NH4Cl and water sequentially, then dried over MgSO4, filtered and concentrated to give a white crude solid (2.92 g, crude product) with some impurity: 1H NMR (400 MHz, MeOD) δ ppm 7.14 (d, J=8.6 Hz, 2H), 6.76 (d, J=8.6 Hz, 2H), 4.56 (m, 1H), 3.63 (m, 2H), 1.43 (s, 9H); LCMS (ESI) m/e 254.1 [(M+H)+, calcd for C13H20NO4 254.3]. with stirring The reaction mixture was transferred to a separatory funnel The aqueous layer was extracted with ethyl acetate (3×30 ml) The combined organic layers were washed with saturated NH4Cl and water sequentially dried over MgSO4 filtered concentrated to give a white crude solid (2.92 g, crude product) with some impurity

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

Procedure: (R)-(−)-2-phenylglycine methyl ester hydrochloride (2.17 g, 10 mmol) and di-t-butyl di-carbonate (2.62 g, 12 mmol) were combined in tetrahydrofuran (100 ml). Triethylamine (1.60 ml, 22 mmol) was added to the mixture via syringe at room temperature. The reaction mixture was stirred at room temperature overnight. The THF in reaction mixture was then removed in vacuum. Saturated aqueous NH4Cl and ethyl acetate were added to the mixture in a separatory funnel. The aqueous layer was extracted with ethyl acetate (3×40 ml). The combined organic layer was washed with saturated aqueous NH4Cl, dried over MgSO4, filtered and concentrated to give a white solid (3.08 g, crude product): 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.20 (d, J=8.1 Hz, 2H), 6.77 (m, 2H), 5.73 (br. s., 1H), 5.56 (br. s., 1H), 5.25 (d, J=6.6 Hz, 1H), 3.73 (s, 3H), 1.46 (s, 9H) LCMS (ESI) m/e 282.1 [(M+H)+, calcd for C14H20NO5 282.3]. was then removed in vacuum Saturated aqueous NH4Cl and ethyl acetate were added to the mixture in a separatory funnel The aqueous layer was extracted with ethyl acetate (3×40 ml) The combined organic layer was washed with saturated aqueous NH4Cl dried over MgSO4 filtered concentrated to give a white solid (3.08 g, crude product)

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

Procedure: (R)-(−)-2-phenylglycine methyl ester hydrochloride (2.17 g, 10 mmol) and di-t-butyl di-carbonate (2.62 g, 12 mmol) were combined in tetrahydrofuran (100 ml). Triethylamine (1.60 ml, 22 mmol) was added to the mixture via syringe at room temperature. The reaction mixture was stirred at room temperature overnight. The THF in reaction mixture was then removed in vacuum. Saturated aqueous NH4Cl and ethyl acetate were added to the mixture in a separatory funnel. The aqueous layer was extracted with ethyl acetate (3×40 ml). The combined organic layer was washed with saturated aqueous NH4Cl, dried over MgSO4, filtered and concentrated to give a white solid (3.08 g, crude product): 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.20 (d, J=8.1 Hz, 2H), 6.77 (m, 2H), 5.73 (br. s., 1H), 5.56 (br. s., 1H), 5.25 (d, J=6.6 Hz, 1H), 3.73 (s, 3H), 1.46 (s, 9H) LCMS (ESI) m/e 282.1 [(M+H)+, calcd for C14H20NO5 282.3]. was then removed in vacuum Saturated aqueous NH4Cl and ethyl acetate were added to the mixture in a separatory funnel The aqueous layer was extracted with ethyl acetate (3×40 ml) The combined organic layer was washed with saturated aqueous NH4Cl dried over MgSO4 filtered concentrated to give a white solid (3.08 g, crude product)

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

Procedure: A 0° C. solution of (R)-Methyl 2-(tert-butoxycarbonylamino)-2-(4-hydroxyphenyl)acetate (2.8 g, 10 mmol), (S)-2-methyl-1-butanol (1.1 mL, 10 mmol), triphenylphosphine (2.6 g, 10 mmol), and tetrahydrofuran (100 mL) was treated dropwise with diisopropylazodicarboxylate (1.9 mL, 10 mmol) via syringe. The resulting reaction mixture was allowed to warm to room temperature and maintained overnight. The reaction was concentrated and the residue was purified by column chromatography on silica gel (5%→10% ethyl acetate in hexanes) to afford (2R)-methyl 2-(tert-butoxycarbonylamino)-(4-((S)-2-methyl-butoxy)-phenyl)acetate (2.8 g, 80% yield) as a clear, colorless oil: 1H NMR (400 MHz, CDCl3) δ 7.27 (d, J=7.3 Hz, 2H), 6.88 (d, J=8.6 Hz, 2H), 5.49 (d, J=6.6 Hz, 1H), 5.26 (d, J=7.3 Hz, 1H), 3.81 (dd, J=9.1, 6.1 Hz, 1H), 3.73 (s, 3H), 3.69-3.76 (m, 1H), 1.86 (dq, J=13.1, 6.5 Hz, 1H), 1.52-1.61 (m, 1H), 1.45 (s, 9H), 1.22-1.33 (m, 2H), 1.02 (d, J=6.8 Hz, 3H), 0.95 (t, J=7.5 Hz, 3H); LRMS (ESI) m/e 352.2 [(M+H)+, calcd for C19H30NO5 352.5]. The resulting reaction mixture maintained overnight The reaction was concentrated the residue was purified by column chromatography on silica gel (5%→10% ethyl acetate in hexanes)

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

Procedure: (R)-methyl 2-(tert-butoxycarbonylamino)-2-(4-hydroxyphenyl)acetate (23.00 g, 82 mmol), 2-methylpentan-1-ol (16.70 g, 163 mmol), and triphenylphosphine (36.46 g, 139 mmol) were combined in tetrahydrofuran (600 mL). After stirring 10 min, diethylazodicarboxylate (21.9 mL, 138 mmol) was added via syringe at room temperature. The reaction was mildly exothermic resulting in the temperature rising to the mid thirties ° C. during the addition. Intermittent cooling with a tap water bath was used to prevent the reaction mixture temperature from rising higher than this, but it was not cooled down to room temperature during the addition. After the addition was complete, the mixture was stirred at room temperature for 18 h. The reaction mixture was transferred to a separatory funnel containing water (400 mL). The aqueous layer was extracted with ether (3×400 mL). The combined organic layers were washed with brine (250 mL), dried over MgSO4, filtered and concentrated. The crude product was taken up in ether (ca. 800 mL) and was stirred for 30 min. The mixture was filtered through a pad of diatomaceous earth (Celite®) to remove most of the triphenylphosphine oxide and the filtrate was concentrated. The residue was purified by column chromatography on silica gel (20% ethyl acetate in hexanes) to afford (2R)-methyl 2-(tert-butoxycarbonylamino)-2-(4-(2-methylpentyloxy)phenyl)acetate (29.43 g, 98% yield) as a colorless oil: 1H NMR (400 MHz, CDCl3) δ 7.20-7.29 (m, 2H), 6.84 (d, J=8.6 Hz, 2H), 5.45 (d, J=6.5 Hz, 1H), 5.22 (d, J=7.3 Hz, 1H), 3.77 (dd, J=9.1, 5.8 Hz, 1H), 3.69 (s, 3H), 3.65-3.70 (m, 1H), 1.85-1.96 (m, 1H), 1.41 (s, 9H), 1.14-1.50 (m, 4H), 0.98 (d, J=6.8 Hz, 3H), 0.90 (t, J=7.1 Hz, 3H); LRMS (ESI) m/e 366.4 [(M+H)+, calcd for C20H32NO5 366.2]. The reaction was mildly exothermic resulting in the temperature during the addition Intermittent cooling with a tap water bath After the addition the mixture was stirred at room temperature for 18 h The reaction mixture was transferred to a separatory funnel The aqueous layer was extracted with ether (3×400 mL) The combined organic layers were washed with brine (250 mL) dried over MgSO4 filtered concentrated was stirred for 30 min The mixture was filtered through a pad of diatomaceous earth (Celite®) to remove most of the triphenylphosphine oxide the filtrate was concentrated The residue was purified by column chromatography on silica gel (20% ethyl acetate in hexanes)

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

Procedure: The title compound was prepared from the product from step 1 (1.3 g, 4.6 mmol) and 4-iododiphenylmethane (2.0 g, 6.9 mmol) using the Step 4 procedure of example 1 with 50% yield (1.1 g). 1HNMR (CDCl3) 1.43 (s, 9H), 3.73 (s, 3H), 3.97 (s, 2H), 5.29 (m, 1H), 5.50 (m, 1H), 6.94 (m, 4H), 7.15 (d, J=6.8 Hz, 2H), 7.20 (m, 3H), 7.30 (m, 4H), MS m/z 448 (M+1).

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

Procedure: A 0° C. solution of (R)-Methyl 2-(tert-butoxycarbonylamino)-2-(4-hydroxyphenyl)acetate (2.8 g, 10 mmol), (S)-2-methyl-1-butanol (1.1 mL, 10 mmol), triphenylphosphine (2.6 g, 10 mmol), and tetrahydrofuran (100 mL) was treated dropwise with diisopropylazodicarboxylate (1.9 mL, 10 mmol) via syringe. The resulting reaction mixture was allowed to warm to room temperature and maintained overnight. The reaction was concentrated and the residue was purified by column chromatography on silica gel (5%-10% ethyl acetate in hexanes) to afford (2R)-Methyl 2-(tert-butoxycarbonylamino)-(4-((S)-2-methyl-butoxy)-phenyl)acetate (2.8 g, 80% yield) as a clear, colorless oil: 1H NMR (400 MHz, CDCl3) δ 7.27 (d, J=7.3 Hz, 2H), 6.88 (d, J=8.6 Hz, 2H), 5.49 (d, J=6.6 Hz, 1H), 5.26 (d, J=7.3 Hz, 1H), 3.81 (dd, J=9.1, 6.1 Hz, 1H), 3.73 (s, 3H), 3.69-3.76 (m, 1H), 1.86 (dq, J=13.1, 6.5 Hz, 1H), 1.52-1.61 (m, 1H), 1.45 (s, 9H), 1.22-1.33 (m, 2H), 1.02 (d, J=6.8 Hz, 3H), 0.95 (t, J=7.5 Hz, 3H); LRMS (ESI) m/e 352.2 [(M+H)+, calcd for C19H30NO5 352.5]. The resulting reaction mixture maintained overnight The reaction was concentrated the residue was purified by column chromatography on silica gel (5%-10% ethyl acetate in hexanes)

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

Procedure: (R)-tert-Butoxycarbonylamino-(4-hydroxy-phenyl)-acetic acid methyl ester (10 mmol), Lithium Boron hydride (1.089 g, 50 mmol) and THF (50 ml) were combined and stirred at room temperature overnight. Ice (20 ml) was added into the reaction mixture with stirring. Saturated citric acid was then added dropwise until no more bubbles were generated. The reaction mixture was transferred to a separatory funnel. The aqueous layer was extracted with ethyl acetate (3×30 ml). The combined organic layers were washed with saturated NH4Cl and water sequentially, then dried over MgSO4, filtered and concentrated to give a white crude solid (2.92 g, crude product) with some impurity: 1H NMR (400 MHz, MeOD) δ ppm 7.14 (d, J=8.6 Hz, 2H), 6.76 (d, J=8.6 Hz, 2H), 4.56 (m, 1H), 3.63 (m, 2H), 1.43 (s, 9H); LCMS (ESI) m/e 254.1 [(M+H)+, calcd for C13H20NO4 254.3]. with stirring The reaction mixture was transferred to a separatory funnel The aqueous layer was extracted with ethyl acetate (3×30 ml) The combined organic layers were washed with saturated NH4Cl and water sequentially dried over MgSO4 filtered concentrated to give a white crude solid (2.92 g, crude product) with some impurity

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

Procedure: (R)-(−)-2-phenylglycine methyl ester hydrochloride (2.17 g, 10 mmol) and di-t-butyl di-carbonate (2.62 g, 12 mmol) were combined in tetrahydrofuran (100 ml). Triethylamine (1.60 ml, 22 mmol) was added to the mixture via syringe at room temperature. The reaction mixture was stirred at room temperature overnight. The THF in reaction mixture was then removed in vacuum. Saturated aqueous NH4Cl and ethyl acetate were added to the mixture in a separatory funnel. The aqueous layer was extracted with ethyl acetate (3×40 ml). The combined organic layer was washed with saturated aqueous NH4Cl, dried over MgSO4, filtered and concentrated to give a white solid (3.08 g, crude product): 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.20 (d, J=8.1 Hz, 2H), 6.77 (m, 2H), 5.73 (br. s., 1H), 5.56 (br. s., 1H), 5.25 (d, J=6.6 Hz, 1H), 3.73 (s, 3H), 1.46 (s, 9H) LCMS (ESI) m/e 282.1 [(M+H)+, calcd for C14H20NO5 282.3]. was then removed in vacuum Saturated aqueous NH4Cl and ethyl acetate were added to the mixture in a separatory funnel The aqueous layer was extracted with ethyl acetate (3×40 ml) The combined organic layer was washed with saturated aqueous NH4Cl dried over MgSO4 filtered concentrated to give a white solid (3.08 g, crude product)