1: ethyl acetate With n-butyllithium; 1,1,1,3,3,3-hexamethyl-disilazane in tetrahydrofuran; hexane T=-78°C; 0.25 h; 2: kumujancine in tetrahydrofuran; hexane T=-78°C; 0.25 h; 3: With ethanol in tetrahydrofuran; hexane T=20°C; 0.5 h;

2,3-dicyano-5,6-dichloro-p-benzoquinone in 1,4-dioxane Heating;

potassium tert-butylate in dimethyl sulfoxide T=100°C; 0.75 h;

1: 6percent aq. NH4OH / methanol / 2 h / Heating 2: p-toluenesulfonic acid (pTSA) / dioxane; benzene / 48 h / Heating; azeotropic removal of water 3: 70 percent / dichlorodicyanobenzoquinone (DDQ) / dioxane / 10 h / Heating View Scheme

1: 92 percent / methanol / 20 h / Heating 2: 77 percent / dichlorodicyanobenzoquinone (DDQ) / tetrahydrofuran; H2O / 24 h / Ambient temperature 3: 88 percent / concd HCl / acetic acid / 3 h / Heating 4: 51 percent / p-toluenesulfonic acid (pTSA), trimethyl orthoformate / 24 h / Heating 5: 6percent aq. NH4OH / methanol / 2 h / Heating 6: p-toluenesulfonic acid (pTSA) / dioxane; benzene / 48 h / Heating; azeotropic removal of water 7: 70 percent / dichlorodicyanobenzoquinone (DDQ) / dioxane / 10 h / Heating View Scheme

1: 77 percent / dichlorodicyanobenzoquinone (DDQ) / tetrahydrofuran; H2O / 24 h / Ambient temperature 2: 88 percent / concd HCl / acetic acid / 3 h / Heating 3: 51 percent / p-toluenesulfonic acid (pTSA), trimethyl orthoformate / 24 h / Heating 4: 6percent aq. NH4OH / methanol / 2 h / Heating 5: p-toluenesulfonic acid (pTSA) / dioxane; benzene / 48 h / Heating; azeotropic removal of water 6: 70 percent / dichlorodicyanobenzoquinone (DDQ) / dioxane / 10 h / Heating View Scheme

1: 51 percent / p-toluenesulfonic acid (pTSA), trimethyl orthoformate / 24 h / Heating 2: 6percent aq. NH4OH / methanol / 2 h / Heating 3: p-toluenesulfonic acid (pTSA) / dioxane; benzene / 48 h / Heating; azeotropic removal of water 4: 70 percent / dichlorodicyanobenzoquinone (DDQ) / dioxane / 10 h / Heating View Scheme

1: 88 percent / concd HCl / acetic acid / 3 h / Heating 2: 51 percent / p-toluenesulfonic acid (pTSA), trimethyl orthoformate / 24 h / Heating 3: 6percent aq. NH4OH / methanol / 2 h / Heating 4: p-toluenesulfonic acid (pTSA) / dioxane; benzene / 48 h / Heating; azeotropic removal of water 5: 70 percent / dichlorodicyanobenzoquinone (DDQ) / dioxane / 10 h / Heating View Scheme

1.1: 70 percent / DIBALH / CH2Cl2 / 0.08 h / -40 °C 2.1: HMDS; n-BuLi / tetrahydrofuran; hexane / 0.25 h / -78 °C 2.2: tetrahydrofuran; hexane / 0.25 h / -78 °C 2.3: 88 percent / EtOH / tetrahydrofuran; hexane / 0.5 h / 20 °C View Scheme

potassium carbonate in acetone Heating;