Brønstedacidscatalyze the addition of enolizable β-keto esters to α,β-unsaturated aldehydes leading to substituted 2H-pyrans in good yields under mild conditions via a formal [3+3] cycloaddition.
A Lewis Acid-Catalyzed Formal [3 + 3] Cycloaddition of α,β-Unsaturated Aldehydes with 4-Hydroxy-2-Pyrone, Diketones, and Vinylogous Esters
作者:Aleksey V. Kurdyumov、Nan Lin、Richard P. Hsung、Glen C. Gullickson、Kevin P. Cole、Nadiya Sydorenko、Jacob J. Swidorski
DOI:10.1021/ol0523042
日期:2006.1.1
A Lewis acid-catalyzed formal cycloaddition of alpha,beta-unsaturated aldehydes with 6-methyl-4-hydroxy-2-pyrone, 1,3-diketones, and vinylogous silyl esters is described here.
A Formal [3 + 3] Cycloaddition Reaction. Improved Reactivity Using α,β-Unsaturated Iminium Salts and Evidence for Reversibility of 6π-Electron Electrocyclic Ring Closure of 1-Oxatrienes
作者:Hong C. Shen、Jiashi Wang、Kevin P. Cole、Michael J. McLaughlin、Christopher D. Morgan、Christopher J. Douglas、Richard P. Hsung、Heather A. Coverdale、Aleksey I. Gerasyuto、Juliet M. Hahn、Jia Liu、Heather M. Sklenicka、Lin-Li Wei、Luke R. Zehnder、Craig A. Zificsak
DOI:10.1021/jo020688t
日期:2003.3.1
A detailed account regarding a formal [3 + 3] cycloaddition method using 4-hydroxy-2-pyrones and 1,3-diketones is described here. This formal cycloaddition reaction or annulation reaction is synthetically useful for constructing 2H-pyranyl heterocycles. The usage of alpha,beta-unsaturated iminium salts is significant in controlling competing reaction pathways to give exclusively 2H-pyrans. Most significantly, experimental evidence is provided to support the mechanism of this reaction that involves a sequential Knoevenagel condensation and a reversible 6pi-electron electrocyclic ringclosure of 1-oxatrienes.
Sequential 1,2-Addition−Electrocyclic Ring Closures Involving Acyclic α,β-Unsaturated Iminiums: A Formal [3 + 3] Cycloaddition Strategy to Unique Pyranyl Spirocycles
作者:Richard P. Hsung、Hong C. Shen、Christopher J. Douglas、Christopher D. Morgan、Shane J. Degen、Letitia J. Yao
DOI:10.1021/jo982165k
日期:1999.2.1
March, P. de; Moreno-Manas, M.; Casado, J., Journal of Heterocyclic Chemistry, 1984, vol. 21, # 1, p. 85 - 89
作者:March, P. de、Moreno-Manas, M.、Casado, J.、Pleixats, R.、Roca, J. L.、Trius, A.