(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• pseudooligosaccharide 42 with different secondary amines gave the corresponding guanidines 43–46 (Scheme 5) and their conformational behaviour and tautomerism was studied by NMR spectroscopy. β(1→6)-Linked pseudodi- (47) and pseudotrisaccharides (48) incorporating guanidine intersaccharide bridges have been prepared

C₂-symmetric bisamidines: Chiral Brønsted bases catalysing the Diels- Alder reaction of anthrones

• Deniz Akalay,
• Gerd Dürner,
• Jan W. Bats and
• Michael W. Göbel

Beilstein J. Org. Chem. 2008, 4, No. 28, doi:10.3762/bjoc.4.28

• reaction of anthrones 1 and maleimides 2 catalyzed by chiral Brønsted bases 4–8. Protonation states and tautomerism of C2-symmetric bisamidine 8a [6]. Synthesis of C2-symmetric bisamidines 8b–c and ent-8d. Proposed mechanism of the Diels-Alder reaction. First evaluation step of chiral bisamidine catalysts

Variations in product in reactions of naphthoquinone with primary amines

• Marjit W. Singh,
• Anirban Karmakar,
• Nilotpal Barooah and
• Jubaraj B. Baruah

Beilstein J. Org. Chem. 2007, 3, No. 10, doi:10.1186/1860-5397-3-10

• with dD-H, 0.889 Å, dH-A 2.287 Å, dD-A 3.151 Å, Tautomerism of the imine and amine group

• leads to the desired product. Valence tautomerism is commonly observed in metal complexes of 1,2-quinonic compounds. [16][17][18][19][20][21][22] In our reactions two moles of amines are used; with one mole of 1,2-naphthoquinone the same product is obtained as with 1:1 stoichiometry between amine and

Efficient synthesis of 5-substituted 2-aryl- 6-cyanoindolizines via nucleophilic substitution reactions

• Eugene V. Babaev,
• Natalya I. Vasilevich and
• Anna S. Ivushkina

Beilstein J. Org. Chem. 2005, 1, No. 9, doi:10.1186/1860-5397-1-9

• the structure A for indolizinones 1, we assumed the existence of tautomerism between forms A and B involving hydrogen interchange between oxygen and C-3 carbon (Scheme 1). Although the amount of tautomer B is negligibly small, one would expect that treatment of 1 a – d with phosphorous oxychloride may