1: carbonic acid 2-bromo-3-tert-butoxycarbonyloxy-6-formyl-phenyl ester tert-butyl ester With sodium tetrahydroborate in tetrahydrofuran; water T=0°C; 0.00333333 h; 2: isopropylmagnesium chloride in diethyl ether T=-78 - 20°C; 4.16667 h;

1: carbonic acid 2-bromo-3-tert-butoxycarbonyloxy-6-formyl-phenyl ester tert-butyl ester With sodium tetrahydroborate in tetrahydrofuran; water T=0°C; 0.00833333 h; 2: chloro-(2-methylpropyl)magnesium in tetrahydrofuran T=20°C; 4 h; Further stages.;

1: 4-dimethylaminopyridine; diisopropylethylamine / tetrahydrofuran / 8 h 2: NaBH4 / H2O; tetrahydrofuran / 0 °C 3: diethyl ether / -78 - 20 °C View Scheme

1: 4-dimethylaminopyridine; diisopropylethylamine / tetrahydrofuran / 8 h 2: NaBH4 / H2O; tetrahydrofuran / 0 °C 3: diethyl ether / -78 - 20 °C View Scheme

1: NaBH4 / H2O; tetrahydrofuran / 0 °C 2: diethyl ether / -78 - 20 °C View Scheme

in diethyl ether T=-78 - 20°C;