Unusual cyclopropanation of 9-bromocamphor derivatives: a novel formal C(1)-C(7) bond cleavage of camphor.
[reaction: see text] An unusual cyclopropanation of 9-bromocamphor derivatives 1 to a 7-spiro-cyclopropyl camphor derivative 3 was effected by the action of potassium tert-butoxide (or sodium hydride) in warm DMSO. The exo-hydroxy group and a non-hydrogen endo-substituent at C(2) have proven to be essential structural elements, and the solvent DMSO has proven to be the sole effective reaction medium. Tricyclic compound 3 undergoes a facile tandem Wagner-Meerwein rearrangement-cyclopropyl ring-opening under mild acidic conditions, leading to norbornenyl derivative 12 and subsequent Meinwald rearrangement of bicyclic epoxide 13 to a formal C(1)-C(7) bond cleavage product 14.
Li
Wei-Dong Z
WD
State Key Laboratory of Applied Organic Chemistry, Lanzhou University, China.
Yang
Yu-Rong
YR
D002164:Camphor / Q000031:analogs & derivatives / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D013237:Stereoisomerism
C509584:9-bromocamphor; D002164:Camphor; D004121:Dimethyl Sulfoxide