Synthesis of benzofuranyl indolinones and benzonaphthoxazepinones <i>via</i> reaction of sulfonyl phthalide with nitroisatylidenes

The attempted [4 + 2] Hauser-Kraus annulation of sulfonyl phthalide with nitroisatylidenes led to the formation of benzofuranyl indolinones, instead of the expected spironaphthoquinone oxindoles, <i>via</i> nucleophilic vinylic substitution of the nitro group. In contrast, the reaction of sulfonyl phthalide with nitroisoxazolyl isatylidenes followed the [4 + 2] Hauser-Kraus pathway, yielding benzonaphthoxazepinones <i>via</i> spontaneous rearrangement of the initially formed Hauser-Kraus adducts, namely, spironaphthoquinone oxindoles.