Grubb's 2nd generation catalyst in dichloromethane T=40°C; 3 h; Inert atmosphere; optical yield given as percent dediastereoselective reaction;

1: N-Ethylidene-1,1-dimethylethylamine With lithium diisopropyl amide in tetrahydrofuran; n-heptane T=-78°C; 0.5 h; 2: diethyl chlorophosphate in tetrahydrofuran; n-heptane T=-78 - -10°C; 3 h; 3: 4-hydroxybutyraldehyde tert-butyldimethylsilyl ether in tetrahydrofuran; n-heptane T=-78 - 20°C; 2 h; Further stages.;

Grubb's 2nd generation catalyst in dichloromethane T=40°C; cross metathesis; 3 h;

1.1: (COCl)2; DMSO; Et3N / CH2Cl2 / 0.83 h / -60 - -20 °C 2.1: NaH / tetrahydrofuran / 0.5 h / -20 °C 2.2: 80 percent / tetrahydrofuran / 0.83 h / -20 - 20 °C 3.1: 84 percent / DIBALH / CH2Cl2; hexane / 0.33 h / -60 °C 4.1: 94 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -60 - -20 °C View Scheme

1.1: NaH / tetrahydrofuran / 1 h 1.2: 97 percent / tetrahydrofuran / 1 h / 20 °C 2.1: (COCl)2; DMSO; Et3N / CH2Cl2 / 0.83 h / -60 - -20 °C 3.1: NaH / tetrahydrofuran / 0.5 h / -20 °C 3.2: 80 percent / tetrahydrofuran / 0.83 h / -20 - 20 °C 4.1: 84 percent / DIBALH / CH2Cl2; hexane / 0.33 h / -60 °C 5.1: 94 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -60 - -20 °C View Scheme

1.1: NaH / tetrahydrofuran / 0.5 h / -20 °C 1.2: 80 percent / tetrahydrofuran / 0.83 h / -20 - 20 °C 2.1: 84 percent / DIBALH / CH2Cl2; hexane / 0.33 h / -60 °C 3.1: 94 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -60 - -20 °C View Scheme

1: 84 percent / DIBALH / CH2Cl2; hexane / 0.33 h / -60 °C 2: 94 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -60 - -20 °C View Scheme

in benzene 24 h; Heating;

2: 75 percent / pyridine / 1.) 0 deg C, 30 min, 2.) room temperature, 18 h 3: 76 percent / TBAF / tetrahydrofuran / 12 h / 50 °C 4: 1.) NaH / 1.) THF, room temperature, 30 min, 2.) 40 min 5: 85 percent / (COCl)2, DMSO, Et3N / CH2Cl2 / -78 - 20 °C 6: 81 percent / InCl3 / ethyl acetate 7: 94 percent / i-Pr2NEt 8: 90 percent / H2 / Rh/Al2O3 9: 94 percent / TBAF 10: 84 percent / Et3N, DMAP 11: 94 percent / pyridine 12: 83 percent / LiEt3BH 13: 95 percent / TBAF 14: (COCl)2, DMSO, Et3N 15: 75 percent / CrCl2 16: 74 percent / Pd(PPh3)2Cl2, Et2NH, CuI 17: 80 percent / TsNHNH2, NaOAc 18: 80 percent / PPTS / ethanol / 16 h / 75 °C View Scheme