Polyene Cyclization Promoted by the Cross-Conjugated α-Carbalkoxy Enone System. Observation on a Putative 1,5-Hydride/1,3-Alkyl Shift under Lewis Acid Catalysis
作者:Ho-Hsuan Chou、Huang-Min Wu、Jen-Dar Wu、Tai Wei Ly、Ning-Wei Jan、Kak-Shan Shia、Hsing-Jang Liu
DOI:10.1021/ol702631q
日期:2008.1.1
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
Like an enzyme: Asymmetric hydrolysis of enolesters is accomplished by chiral phase‐transfer catalysts under biphasic base hydrolysis conditions. Stoichiometric reactions support the generation of a well‐organized chiral ammonium hydroxide species (Q+OH−).