New synthesis of all four isomers of 3-hydroxy-4-methyl-γ-butyrolactone by stereoselective intramolecular lactonization. Application to asymmetric synthesis of biologically active compounds

Article abstract of DOI:10.1021/jo00103a008

A new synthesis of all four isomeric 3-hydroxy-4-methyl-γ-butyrolactones (11, ent-11, 12, ent-12) has been performed. The former two were prepared via stereoselective iodolactonization, which favors the cis-3,4-disubstituted system (16a and ent-16a), of N-benzyl-N-methyl-3-hydroxy-4-pentenamides(R)- and (S)-13, readily available by resolution of the racemate by lipase-mediated transesterification; and the latter two were prepared via stereoselective oxylactonization, which favors the trans-3,4-disubstituted system [(3R,4S)-20a and ent-(3P,4S)-20a], of O-TBDMS-protected N-benzyl-N-methyl-3-hydroxy-4-pentenamides (R)- and (S)-14. Butyrolactones 11 and 12 have been readily transformed into biologically active compounds [(-)-blastmycinolactol (27), (-)-NFX-2 (2), (-)-NFX-4 (3), lipid metabolites 9 and 10, and the sex pheromone (-)-(2S,3S)-2,3-octanediol (30)].