An operationally simple protocol for the synthesis of medium‐sized lactones and macrolactones via an intramolecular ring expansion of cyclic ketones has been developed. Using this method, a series of 10‐ and 12‐membered lactones was synthesized under mild conditions. Preliminary mechanistic studies showed that a radical pathway might be involved in this reaction.

Bioassay-guided isolation of spiroaspertrione A from cultures of Aspergillus sp. TJ23 in 2017 demonstrated potent resensitization of oxacillin against methicillin-resistant Staphylococcus aureus by lowering the oxacillin minimal inhibitory concentration up to 32-fold. To construct this unique spiro[bicyclo[3.2.2]nonane-2,1′-cyclohexane] system, a protocol for ceric ammonium nitrate-induced intramolecular cross-coupling of silyl enolate is disclosed.