Polyene cyclization promoted by the cross-conjugated alpha-carbalkoxy enone system. Observation on a putative 1,5-hydride/1,3-alkyl shift under Lewis acid catalysis.
Polyene cyclization of compounds 3 and 4 under catalysis with AlCl3 and/or SnCl4 gave rise to complex bicyclic products 8 and 9, structures of which were highly unexpected, and X-ray analyses were invoked for unambiguously structural identification. Mechanistically, a tandem sigma-bond rearrangement process, including an unusual through-space 1,5-hydride or 1,3-alkyl shift as a key operation, is proposed.
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30013, ROC.
Ho-Hsuan
HH
Chou
Huang-Min
HM
Wu
Jen-Dar
JD
Wu
Tai Wei
TW
Ly
Ning-Wei
NW
Jan
Kak-Shan
KS
Shia
Hsing-Jang
HJ
Liu
D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D002934:Cinnamates / Q000737:chemistry; D003500:Cyclization; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry
D000475:Alkenes; D002934:Cinnamates; D007659:Ketones; D015032:Zinc