Rearrangements of bicyclic nitrones to lactams: comparison of photochemical and modified Barton conditions.
The rearrangement of nitrones to lactams can be carried out by photochemical activation or by treatment with Tf(2)O followed by KOH-promoted rearrangement (a modification of conditions originally introduced by Barton). Substrates in which the nitrone is part of a fused bicyclic ring system have traditionally proven problematic for this kind of reaction. In this study, a series of mono-, bi-, and tricyclic ring-fused nitrones were prepared to investigate the dependence of products on nitrone ring size and tether length. Results indicated that photochemical rearrangement of nitrones in benzene afforded reasonably good yields (30-68%) of lactams, while the two-step nonphotochemical process provided slightly better average yields (30-95%) of the same targets.
Zeng
Yibin
Y
Department of Medicinal Chemistry, 1251 Wescoe Hall Drive, Room 4070, Malott Hall, University of Kansas, Lawrence, Kansas 66045-7852, USA.
Smith
Brenton T
BT
Hershberger
John
J
Aubé
Jeffrey
J
D001643:Bridged Bicyclo Compounds / Q000737:chemistry*; D007769:Lactams / Q000737:chemistry*; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000737:chemistry*; D010777:Photochemistry
D001643:Bridged Bicyclo Compounds; D007769:Lactams; D009589:Nitrogen Oxides; C015388:nitrones