1: KN(Me4Si)2 / tetrahydrofuran; dimethylformamide 2: 1.) O3, 2.) (CH3)2S / 1.) MeOH, - 60 deg C 3: CHCl3 / Heating 4: dibal / diethyl ether / -78 - 0 °C 5: TEA,DMAP / CH2Cl2 View Scheme

1: KN(Me4Si)2 / tetrahydrofuran; dimethylformamide 2: 1.) O3, 2.) (CH3)2S / 1.) MeOH, - 60 deg C View Scheme

1: KN(Me4Si)2 / tetrahydrofuran; dimethylformamide 2: 1.) O3, 2.) (CH3)2S / 1.) MeOH, - 60 deg C 3: CHCl3 / Heating 4: dibal / diethyl ether / -78 - 0 °C View Scheme

KN(Me4Si)2 in tetrahydrofuran; N,N-dimethyl-formamide Yield given;

4-(N,N-dimethlyamino)pyridine in tetrahydrofuran; N,N-dimethyl-formamide Heating;

1: 75 percent / TEA,DMAP / tetrahydrofuran; dimethylformamide / Heating 2: 1.) O3, 2.) Me2S / 1.) MeOH, - 60 deg C View Scheme

1: 75 percent / TEA,DMAP / tetrahydrofuran; dimethylformamide / Heating 2: 1.) O3, 2.) Me2S / 1.) MeOH, - 60 deg C 3: 56 percent / KN(Me4Si)2, 18-C-6 / tetrahydrofuran 4: dibal / diethyl ether / -78 - 0 °C 5: TEA, DMAP / CH2Cl2 6: 48percent aq. HF / acetonitrile / 0 °C 7: 81 percent / NaHCO3, I2 / CH2Cl2 / 1.5 h / 0 °C View Scheme

1: KN(Me4Si)2 / tetrahydrofuran; dimethylformamide 2: 1.) O3, 2.) (CH3)2S / 1.) MeOH, - 60 deg C View Scheme

1: 75 percent / TEA,DMAP / tetrahydrofuran; dimethylformamide / Heating 2: 1.) O3, 2.) Me2S / 1.) MeOH, - 60 deg C 3: 56 percent / KN(Me4Si)2, 18-C-6 / tetrahydrofuran View Scheme

1: 75 percent / TEA,DMAP / tetrahydrofuran; dimethylformamide / Heating 2: 1.) O3, 2.) Me2S / 1.) MeOH, - 60 deg C 3: 56 percent / KN(Me4Si)2, 18-C-6 / tetrahydrofuran 4: dibal / diethyl ether / -78 - 0 °C 5: TEA, DMAP / CH2Cl2 6: 48percent aq. HF / acetonitrile / 0 °C 7: 81 percent / NaHCO3, I2 / CH2Cl2 / 1.5 h / 0 °C 8: 54 percent / 1.) AgBF4, 2.) H2O / 48 h / 21 °C View Scheme