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

With  hydrogenchloride in  acetic acid 3 h;  Heating;   

Multi-step reaction with 2 steps 1: 88 percent / concd HCl / acetic acid / 3 h / Heating2: 51 percent / p-toluenesulfonic acid (pTSA), trimethyl orthoformate / 24 h / Heating  

Multi-step reaction with 4 steps 1: 88 percent / concd HCl / acetic acid / 3 h / Heating2: 51 percent / p-toluenesulfonic acid (pTSA), trimethyl orthoformate / 24 h / Heating3: 6percent aq. NH4OH / methanol / 2 h / Heating4: p-toluenesulfonic acid (pTSA) / dioxane; benzene / 48 h / Heating; azeotropic removal of water