Mix and calcinate : The tin–tungsten mixed oxide (Sn–W oxide) prepared by calcination of the Sn–W hydroxide at 800 °C acts as an effective and reusable solid catalyst for C? C bond‐forming reactions, such as the cyclization of citronellal, the Diels–Alder reaction, and the cyanosilylation of carbonyl compounds with trimethylsilyl cyanide (see scheme). The observed catalysis was truly heterogeneous, and the recovered catalyst could be reused without loss of its high catalytic performance.
