A Novel Three‐Carbon Ring Expansion Sequence Synthesis of Exaltone® and (±)‐Muscone

Abstract Intramolecular Grignard ‐type reaction of the bromo lactones 3 and 8 affords the macrocycles 10, 11, 12 and 13, 14, 15 , respectively. More efficiently, 10 and 13 are obtained by intramolecular nucleophilic attack of the carbanions derived from the sulfonyl lactones 20 and 22 and in situ reduction of the intermediate sulfones 21 and 23. The macrocylic hydroxy ketones 10 and 13 are converted into Exaltone ® (2) and muscone (1) , respectively.