- The organocatalytic enantioselective [3+2] cycloaddition reaction of α,β-unsaturated aldehydes with azomethine ylides applied to the asymmetric synthesis of densely substituted pyrroloisoquinolines
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The synthesis of densely functionalized pyrrolo[2,1-a]isoquinolines was accomplished using the organocatalytic [3+2] cycloaddition between enals and azomethine ylides under iminium catalysis developed in our group some years ago as the key step. The cyclo
- Iza, Ainara,Ugarriza, Iratxe,Uria, Uxue,Reyes, Efraím,Carrillo, Luisa,Vicario, Jose L.
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p. 8878 - 8884
(2013/09/23)
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- Stereoselective synthesis of chiral IBR2 analogues
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Two stereoselective routes were developed to synthesize optically pure IBR2 analogues 1-16. The first features addition of N-Boc-3-bromoindole 26 to the sulfinamide 25, providing a 1:1 ratio of the separable diasteroisomers 27 and 28 in good yield. In a s
- Qiu, Xiao-Long,Zhu, Jiewen,Wu, Guikai,Lee, Wen-Hwa,Richard Chamberlin
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experimental part
p. 2018 - 2027
(2009/08/07)
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- Intramolecular Generation of Oxonium Ylides from Functionalized Arylcarbenes
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Arylcarbenes carrying alkoxyalkyl groups in the ortho position have been generated by flash pyrolysis and photolysis of appropriate tosylhydrazone sodium salts.In the gas phase and in a aprotic solvents, interaction of the carbenes with the lone electron pairs of oxygen competes efficiently with insertion into C-H bonds.Both five- and six-membered cyclic oxonium ylides have been generated.The ylides 23, 37, 61b, and 74 undergo 1,2 shifts of benzyl groups with ease, even if ring contraction to highly strained benzocyclobutenes is involved (23, 74).The oxonium ylides37 and 61b strongly prefer the nonconcerted Stevens rearrangement to the sigmatropic Sommelet rearrangement, in contrast to analogous ammonium ylides.Alkyl shifts occur to a very minor extent, if at all.Evidence is presented that alcohols intercept both the carbenes and the oxonium ylides.Protonation of the ylides leads to cyclic oxonium ions, which undergo nucleophilic cleavage of the C-O bonds.Acid catalyzed decomposition of the appropriate diazo compounds gives rise to six-membered, but not to five-membered, cyclic oxonium ions, thus confirming the different intramolecular reactivities of arylcarbenes and benzyl cations.The efficiency of carbene interception increases with increasing acidity of the medium, suggesting nucleophilic behavior (protonation) of the arylcarbenes.
- Kirmse, Wolfgang,Kund, Klaus
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p. 1465 - 1473
(2007/10/02)
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