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

With  hydrogenchloride in  acetic acid 3 h;  Heating;   

Multi-step reaction with 3 steps 1: 51 percent / p-toluenesulfonic acid (pTSA), trimethyl orthoformate / 24 h / Heating2: 6percent aq. NH4OH / methanol / 2 h / Heating3: p-toluenesulfonic acid (pTSA) / dioxane; benzene / 48 h / Heating; azeotropic removal of water