pyridine in dichloromethane T=0 - 20°C; Acylation;

1: 100 percent / triethylamine / CH2Cl2 / 2 h / 0 - 20 °C 2: 95 percent / potassium carbonate / acetonitrile / 7 h / Heating 3: 100 percent / pyridine / CH2Cl2 / 13 h / 20 °C View Scheme

1: 95 percent / potassium carbonate / acetonitrile / 7 h / Heating 2: 100 percent / pyridine / CH2Cl2 / 13 h / 20 °C View Scheme

1: 100 percent / triethylamine / CH2Cl2 2: 95 percent / K2CO3 / acetonitrile / 7 h / Heating 3: 100 percent / pyridine / CH2Cl2 / 0 - 20 °C View Scheme

1.1: triethylamine; dicyclohexylboron triflate / CH2Cl2 / 1 h / -78 °C 1.2: 77 percent / 2,6-lutidine / CH2Cl2 / 0.33 h / 0 °C 2.1: LiBH4 / tetrahydrofuran / 9 h / 90 °C View Scheme

1: (1S,2R)-2-(N-benzyl-N-mesitylenesulfonyl)amino-1-phenyl-1-propyl propionate With triethylamine in dichloromethane T=20°C; Masamune anti-aldol reaction; Inert atmosphere; 2: dicyclohexylboron triflate in hexane; dichloromethane T=-78°C; Inert atmosphere; 3: (2S,4E)-2,4-dimethyl-5-iodo-4-pentenal Further stages;