in tetrahydrofuran; diethyl ether T=-20°C; further solvents and temperatures; Yield given. Yields of byproduct given;

acetic acid T=90°C; Hydrolysis; 36 h;

1.1: 84 percent / 1 h / 100 °C 2.1: (R,R)-1-dimethylamino-2-(2-methoxyethoxy)-1,2-diphenylethane; LDA / toluene / 1 h / -78 °C 2.2: MeOH / toluene / 1 h / -45 °C 3.1: 97 percent / aq. AcOH / 36 h / 90 °C View Scheme

1.1: 84 percent / 1 h / 100 °C 2.1: (R,R)-1-dimethylamino-2-(2-methoxyethoxy)-1,2-diphenylethane; LDA / toluene / 1 h / -78 °C 2.2: MeOH / toluene / 1 h / -45 °C 3.1: 97 percent / aq. AcOH / 36 h / 90 °C View Scheme

sodium hydroxide; N-benzyl-N,N,N-triethylammonium chloride; diethyl chlorophosphate in dichloromethane 2 h; Ambient temperature; Yield given;

1: 1.) LDA / 1) THF, -20 deg C, 1 h, 2) THF, -20 deg C, 30 min, -20 deg C --> rt, 1 h 2: N-(2-naphthalenesulfonyl)-D-valine, BH3*THF / various solvent(s) / 3 h / -78 °C 3: n-Bu4NF / tetrahydrofuran / 1 h / Ambient temperature 4: 1.) Me3Al / 1) CH2Cl2, toluene, rt, 30 min; 2) CH2Cl2, toluene. 50-55 deg C, 2 d 5: BnNEt3Cl, (EtO)2P(O)Cl, aq. NaOH / CH2Cl2 / 2 h / Ambient temperature View Scheme

1: 81 percent / 4-MeC6H4SO3H / Heating 2: 1.) LDA / 1) THF, -20 deg C, 1 h, 2) THF, -20 deg C, 30 min, -20 deg C --> rt, 1 h 3: N-(2-naphthalenesulfonyl)-D-valine, BH3*THF / various solvent(s) / 3 h / -78 °C 4: n-Bu4NF / tetrahydrofuran / 1 h / Ambient temperature 5: 1.) Me3Al / 1) CH2Cl2, toluene, rt, 30 min; 2) CH2Cl2, toluene. 50-55 deg C, 2 d 6: BnNEt3Cl, (EtO)2P(O)Cl, aq. NaOH / CH2Cl2 / 2 h / Ambient temperature View Scheme

1: N-(2-naphthalenesulfonyl)-D-valine, BH3*THF / various solvent(s) / 3 h / -78 °C 2: n-Bu4NF / tetrahydrofuran / 1 h / Ambient temperature 3: 1.) Me3Al / 1) CH2Cl2, toluene, rt, 30 min; 2) CH2Cl2, toluene. 50-55 deg C, 2 d 4: BnNEt3Cl, (EtO)2P(O)Cl, aq. NaOH / CH2Cl2 / 2 h / Ambient temperature View Scheme

1: 1.) Me3Al / 1) CH2Cl2, toluene, rt, 30 min; 2) CH2Cl2, toluene. 50-55 deg C, 2 d 2: BnNEt3Cl, (EtO)2P(O)Cl, aq. NaOH / CH2Cl2 / 2 h / Ambient temperature View Scheme