A practical total synthesis of (+)-spirolaxine methyl ether

An efficient and practical total synthesis of (+)-spirolaxine methyl ether is described. The phthalide-aldehyde 3 has been prepared via the Diels-Alder reaction between 1,4-unconjugated diene 5 and a long-chain acetylenic dienophile 6. The carbon framework of spiroketal sulfone 4 has been constructed from monobenzyl protected 1,5-pentanediol and the stereochemistry in both the phthalide portion and the spiroketal portion has been established by the Sharpless asymmetric epoxidation.