tetra(n-butyl)ammonium hydroxide; triethylamine in methanol T=-10°C; 4.5 h;

T=30°C; 3 h; Pseudomonas melanogenum KY 3987 and KY 8540; Yield given;

1: 7-amino-3-hydroxymethyl-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid With sodium hydroxide in methanol; water T=38 - 50°C; 1 h; 2: 2-methoxyimino-2-(fur-2-yl)acetyl chloride in methanol; DMF (N,N-dimethyl-formamide); dichloromethane; isobutyramide; water T=0 - 2°C;

T=30°C; 3 h; Pseudomonas melanogenum KY 3987 and KY 8540; Yield given;

1.1: N,O-bis(trimethylsilyl)acetamide / N,N-dimethyl-acetamide / 0.5 h / 20 °C 1.2: 51.9 percent / N,N-dimethyl-acetamide / 1.5 h / -20 - -10 °C 2.1: ethyl acetate / 1 h / 20 °C 3.1: PBr / tetrahydrofuran / 0.33 h / -5 °C 4.1: ethyl acetate / 5 h / 20 °C 5.1: 4.04 g / aq. Na2CO3 / CH2Cl2 / 1.5 h / 20 °C 6.1: PCl5; pyridine / CH2Cl2 / 1.5 h / 8 - 10 °C 6.2: MeOH / CH2Cl2 / 1.25 h / -20 - -10 °C 6.3: 90 percent / H2O / -50 °C 7.1: 92.4 percent / N,N-dimethylaniline; POCl3 / CH2Cl2 / 1.5 h / -15 - -10 °C 8.1: TFA; anisole / CH2Cl2 / 0 - 5 °C 9.1: 2.54 g / aq. HCOOH / 3 h / 20 °C View Scheme

1.1: diisopropylamine / tetrahydrofuran / -30 °C / Inert atmosphere 1.2: 0.5 h / Inert atmosphere 2.1: hydrogenchloride / ethyl acetate / 1.5 h / -50 °C / Inert atmosphere 3.1: ethyl acetate / 4 h / -50 °C / Inert atmosphere 4.1: water / 1 h / -50 - 20 °C / Inert atmosphere 5.1: water / 0.5 h / 20 °C / Inert atmosphere 6.1: sodium hydrogencarbonate / water / Inert atmosphere 6.2: 20 °C / Inert atmosphere 7.1: formic acid; titanium tetrachloride / dichloromethane / 1.25 h / 0 - 20 °C / Inert atmosphere View Scheme

1.1: diisopropylamine / tetrahydrofuran / -30 °C / Inert atmosphere 1.2: 0.5 h / Inert atmosphere 2.1: hydrogenchloride / ethyl acetate / 1.5 h / -50 °C / Inert atmosphere 3.1: ethyl acetate / 4 h / -50 °C / Inert atmosphere 4.1: water / 1 h / -50 - 20 °C / Inert atmosphere 5.1: water / 0.5 h / 20 °C / Inert atmosphere View Scheme

T=30°C; 3 h; Pseudomonas melanogenum KY 3987 and KY 8540; Yield given;