Formal Asymmetric 1,3-Dipolar Cycloaddition of Azomethine Ylides to (S)-2-p-Tolylsulfinyl-2-cyclopentenone
摘要:
Azomethine ylides, derived from iminoesters 1 and DBU in the presence of silver salts, react with (S)-2-p-tolylsulfinyl-2-cyclopentenone 2 in a completely regio- and endoselective manner but with a low facial selectivity, affording a mixture of two cycloadducts 3 and 4. When the ylides were prepared with LHMDS, only one diastereoisomer 3 was obtained in an almost quantitative yield. A nucleophilic addition/ring closure process easily accounts for the stereochemical results. Compounds 3 were transformed into optically pure 4-oxocyclopenta[c]dihydropyrroles and tetrahydropyrroles by elimination of the sulfinyl group.
Rh(I) catalysed [2+2+2]-cyclotrimerisation of 1,6-diynes with monoynes in combination with stereospecific thermal or Ag(I) catalysed aldimine→(metallo) azomethine ylide→cycloaddition cascades affords rapid access to complex heterocyclic benzene derivatives in one-pot processes with the generation 5 new bonds, 4 stereocentres and 3 rings.
Highly Enantioselective Copper(I)−Fesulphos-Catalyzed 1,3-Dipolar Cycloaddition of Azomethine Ylides
作者:Silvia Cabrera、Ramón Gómez Arrayás、Juan C. Carretero
DOI:10.1021/ja0552186
日期:2005.11.30
The catalyst system formed by Cu(CH3CN)4ClO4 and the planar chiral P,S-ligand Fesulphos behaves as a very efficient chiral Lewis acid in the catalytic asymmetric 1,3-dipolarcycloaddition of azomethine ylides. This catalyst shows a remarkable reactivity at low catalyst loading (0.5-3 mol %), affording in good yields the endo adducts with exceptional levels of enantioselectivity (up to >99% ee). This
Biology-oriented synthesis of benzopyrano[3,4-c]pyrrolidines
作者:Marco Potowski、Christopher Golz、Carsten Strohmann、Andrey P. Antonchick、Herbert Waldmann
DOI:10.1016/j.bmc.2015.02.044
日期:2015.6
A natural product inspired synthesis of 6,6,5-tricyclic compounds via a silver(I)-catalyzed formal 1,3-dipolar cycloaddition of coumarins with α-iminoesters was developed. The reaction proceeds in a stepwise reaction course under formation of the trans-substituted diastereomer with respect to the 1,3-dipole and shows a broad substrate scope.
Diastereoselective 1,3-Dipolar Cycloaddition Reactions between Azomethine Ylides and Chiral Acrylates Derived from Methyl (S)- and (R)-Lactate – Synthesis of Hepatitis C Virus RNA-Dependent RNA Polymerase Inhibitors
作者:Carmen Nájera、M. de Gracia Retamosa、José M. Sansano、Abel de Cózar、Fernando P. Cossío
DOI:10.1002/ejoc.200700267
日期:2007.10
Highly endo-diastereoselective 1,3-dipolarcycloadditions between acrylates derived from methyl (R)- and (S)-lactate, as chiral dipolarophiles, and azomethineylides derived from glycine and α-substituted amino acids are described. The origins of the observed excellent stereocontrol are interpreted on the basis of computational studies on model systems. This methodology was successfully employed for
Asymmetric 1,3-Dipolar Cycloaddition of N-Metalated Azomethine Ylides to Methyl (<i>S</i>)-2-(<i>p</i>-Tolylsulfinyl)acrylate. Synthesis of Optically Pure 2,4,5-Trisubstituted 2,5-Dihydro-1<i>H</i>-pyrroles
作者:José Luis García Ruano、Amelia Tito、M. Teresa Peromingo
DOI:10.1021/jo010797s
日期:2002.2.1
The first 1,3-dipolar reaction of azomethine ylides with opticallypure vinyl sulfoxide are reported. The presence of the sulfinyl group increase the reactivity of the acrylate moiety as a dipolarophile, and the reactions evolve with complete regio- and endo-selectivities. Nevertheless, mixtures of the two diastereoisomers 4 and 5 (75-88% de) resulting from the anti dipole/s-cis dipolarophile and syn