Cyclopentanone Ring Expansion Leading to Functionalized δ-Lactams: Short Synthesis of Simple Sedum Alkaloids
摘要:
Monosubstituted epoxides react with (cyclopentenyloxy)trimethylsilane to afford, after subsequent oxidative fragmentation, a pair of diastereomeric 8-membered iodolactones. When these lactones are separately treated with sodium azide, followed by reduction over Lindlar's catalyst, lactone ring contraction yields 6-membered monosubstituted lactams. When (R)-1,2-epoxypentane is used in this 5 + 3 - 2 overall ring expansion sequence, one final step involving delta-lactam to piperidine reduction yields natural (-)-halosaline and (-)-epihalosaline in five steps and 12% and 23% overall yields, respectively.
Cyclopentanone Ring Expansion Leading to Functionalized δ-Lactams: Short Synthesis of Simple Sedum Alkaloids
摘要:
Monosubstituted epoxides react with (cyclopentenyloxy)trimethylsilane to afford, after subsequent oxidative fragmentation, a pair of diastereomeric 8-membered iodolactones. When these lactones are separately treated with sodium azide, followed by reduction over Lindlar's catalyst, lactone ring contraction yields 6-membered monosubstituted lactams. When (R)-1,2-epoxypentane is used in this 5 + 3 - 2 overall ring expansion sequence, one final step involving delta-lactam to piperidine reduction yields natural (-)-halosaline and (-)-epihalosaline in five steps and 12% and 23% overall yields, respectively.
Cyclopentanone Ring Expansion Leading to Functionalized δ-Lactams: Short Synthesis of Simple Sedum Alkaloids
作者:William A. Maio、Sandra Sinishtaj、Gary H. Posner
DOI:10.1021/ol070960r
日期:2007.7.1
Monosubstituted epoxides react with (cyclopentenyloxy)trimethylsilane to afford, after subsequent oxidative fragmentation, a pair of diastereomeric 8-membered iodolactones. When these lactones are separately treated with sodium azide, followed by reduction over Lindlar's catalyst, lactone ring contraction yields 6-membered monosubstituted lactams. When (R)-1,2-epoxypentane is used in this 5 + 3 - 2 overall ring expansion sequence, one final step involving delta-lactam to piperidine reduction yields natural (-)-halosaline and (-)-epihalosaline in five steps and 12% and 23% overall yields, respectively.