C–C Bond formation catalyzed by natural gelatin and collagen proteins

• Dennis Kühbeck,
• Basab Bijayi Dhar,
• Eva-Maria Schön,
• Carlos Cativiela,
• Vicente Gotor-Fernández and
• David Díaz Díaz

Beilstein J. Org. Chem. 2013, 9, 1111–1118, doi:10.3762/bjoc.9.123

• 33071, Spain 10.3762/bjoc.9.123 Abstract The activity of gelatin and collagen proteins towards C–C bond formation via Henry (nitroaldol) reaction between aldehydes and nitroalkanes is demonstrated for the first time. Among other variables, protein source, physical state and chemical modification

• role in the kinetics of the nitroaldol reaction. Conclusion In conclusion, we have found that natural gelatin and collagen proteins are able to promote C–C bond formation via the Henry (nitroaldol) reaction between various aldehydes and nitroalkanes. Thus, the reaction takes place in both aqueous and

A versatile and efficient approach for the synthesis of chiral 1,3-nitroamines and 1,3-diamines via conjugate addition to new (S,E)-γ-aminated nitroalkenes derived from L-α-amino acids

• Vera Lúcia Patrocinio Pereira,
• André Luiz da Silva Moura,
• Daniel Pais Pires Vieira,
• Leandro Lara de Carvalho,
• Eliz Regina Bueno Torres and
• Jeronimo da Silva Costa

Beilstein J. Org. Chem. 2013, 9, 832–837, doi:10.3762/bjoc.9.95

• derivatives by the use of chiral metal and organocatalysts [55][56]. In contrast, chiral 1,3-nitroamines, despite constituting direct precursors of chiral 1,3-diamines, are scarcely synthesized by conjugate addition of nitroalkanes to nitroalkenes. Chiral 1,3-diamines present extraordinary opportunities in

Easy and direct conversion of tosylates and mesylates into nitroalkanes

• Alessandro Palmieri,
• Serena Gabrielli and
• Roberto Ballini

Beilstein J. Org. Chem. 2013, 9, 533–536, doi:10.3762/bjoc.9.58

• corresponding nitroalkanes, by their treatment with tetrabutylammonium nitrite (TBAN) under mild conditions. Keywords: mesylates; nitroalkanes; nucleophilic substitution; tetrabutylammonium nitrite; tosylates; Introduction Nitroalkanes have proven to be one of the most valuable, versatile classes of

• electron-withdrawing effect of the nitro group, nitroalkanes are prone to afford, under basic conditions, stabilized carbanions, which are commonly used as nucleophiles with a variety of electrophiles [8][9][10][11] leading to carbon–carbon bond formation. Furthermore, by making use of the possibility to

• transform the nitro group into other functionalities, the obtained adducts can be employed as strategic starting materials for the preparation of more complex structures [12][13]. In this context, primary nitroalkanes are the most used nitro derivatives [3][4][5][14][15][16][17], and thus, their

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• . The enolates and their equivalents involved in the reactions discussed in this article were derived from ketones, nitroalkanes, malononitrile and α,β-unsaturated compounds. Keywords: acetophenone; chromane; enolates; malononitrile; Michael addition; salicylaldehyde; Introduction The chromane

Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones

• Sergei Žari,
• Tiiu Kailas,
• Marina Kudrjashova,
• Mario Öeren,
• Ivar Järving,
• Toomas Tamm,
• Margus Lopp and
• Tõnis Kanger

Beilstein J. Org. Chem. 2012, 8, 1452–1457, doi:10.3762/bjoc.8.165

• bicyclic guanidines [7][9][12]. Xiao et al. reported the addition of nitroalkanes to 4-oxo-enoates, using chiral urea derivatives [7]. Miura et al. achieved an asymmetric addition of α,α-disubstituted aldehydes to maleimides catalyzed by primary amine thiourea organocatalyst [13]. Wang et al. reported the

Continuous flow based catch and release protocol for the synthesis of α-ketoesters

• Alessandro Palmieri,
• Steven V. Ley,
• Anastasios Polyzos,
• Mark Ladlow and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2009, 5, No. 23, doi:10.3762/bjoc.5.23

• allow for the complete generation of α-ketoester products in flow from the starting nitroalkanes (Scheme 3). As shown in Table 1, we demonstrate that the synthesis of the nitroolefinic esters was achieved under flow conditions in a clean and effective fashion. Moreover, this synthesis demonstrates the

A convenient synthesis of γ-functionalized cyclopentenones

• Nour Lahmar,
• Taïcir Ben Ayed,
• Moncef Bellassoued and
• Hassen Amri

Beilstein J. Org. Chem. 2005, 1, No. 11, doi:10.1186/1860-5397-1-11

• 3 in a basic medium, led to the functionalized cyclopentenones 4. Keywords: Nef reaction; conjugated addition; nitroalkanes; 1,4-diketones; functionalized cyclopentenones; Introduction The cyclopentenones are considered as an important class of compounds because they are present in a large variety

• conjugate addition of nitroalkanes to α,β-unsaturated ketones 1 leading to the nitroalkanes derivatives 2 which may be converted into their γ-diketone homologues 3 using Nef reaction. The intramolecular cyclization of 1,4-diketones 3 led to the corresponding cyclopentenones 4. Results and discussion As

• previously reported, the 1,4-addition of primary nitroalkanes [7][8][9][10][11][12] to functionalized α,β-unsaturated ketones was considered as an appropriate method to prepare multifunctional nitroketonic compounds. These intermediates are important in organic synthesis because the nitro group can be