Catalytic Environmentally Friendly Protocol for Achmatowicz Rearrangement

The increasing interest in Achmatowicz rearrangement in organic synthesis calls for a more environmentally friendly protocol since the most popular oxidants m-CPBA and NBS produced stoichiometric organic side product (mchlorobenzoic acid or succinimide). Mechanism-guided analysis enables us to develop a new catalytic method (Oxone/KBr) for AchR in excellent yield with K2SO4 as the only side product, which greatly facilitates the purification. This protocol was integrated with other transformations, leading to a. rapid access to the highly functionalized dihydropyranones.