Titanium-mediated reductive cross-coupling reactions of imines with terminal alkynes: An efficient route for the synthesis of stereodefined allylic amines

• Kebin Mao,
• Guoqin Fan,
• Yuanhong Liu,
• Shi Li,
• Xu You and
• Dan Liu

Beilstein J. Org. Chem. 2013, 9, 621–627, doi:10.3762/bjoc.9.69

• substitution reactions [8][9], radical reactions [10] and Pd-catalyzed reactions [11]. Thus, allylic amines have been used for the synthesis of numerous heterocycles and bioactive amines, such as α- and β-amino acids [12][13][14][15], different alkaloids [16], aminoallylsilanes [17], aminoepoxides [18

Efficient synthesis of β’-amino-α,β-unsaturated ketones

• Isabelle Abrunhosa-Thomas,
• Aurélie Plas,
• Nishanth Kandepedu,
• Pierre Chalard and
• Yves Troin

Beilstein J. Org. Chem. 2013, 9, 486–495, doi:10.3762/bjoc.9.52

• incorporating β-amino ketone functionality are prevalent in many natural products of biological importance [1]. This versatile synthon has been extensively used in the construction of β-amino acids [2], β-amino alcohols [3], and homoallylic amines [4][5], and can serve as building blocks for the preparation of

Synthesis of trifunctional cyclo-β-tripeptide templates

• Frank Stein,
• Tahir Mehmood,
• Tilman Plass,
• Javid H. Zaidi and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2012, 8, 1576–1583, doi:10.3762/bjoc.8.180

• -supported route with on-resin cyclization is described, employing the aryl hydrazide linker cleavable by oxidation. An orthogonal protection-group strategy allows functionalization of the central cyclic β-tripeptide with up to three different peptide fragments or fluorescent labels. Keywords: β-amino acids

• prepared from the respective β-amino acids by Arndt–Eistert homologation [17][18][19]. The β-amino acids were transformed into the respective diazoketones with isobutyl chloroformate, triethylamine and diazomethane. The ketones were further converted into the β-amino acids by Wolff rearrangement using

• according to Scheme 1 by using the commercially available 4-Fmoc-hydrazinobenzoyl AM NovaGel resin from Merck Biosciences. After coupling of the three β-amino acids by using the standard Boc-protocol, the hydrazide linker was oxidized to generate nitrogen as a good leaving group. Nucleophilic attack of the

Homoallylic amines by reductive inter- and intramolecular coupling of allenes and nitriles

• Peter Wipf and
• Marija D. Manojlovic

Beilstein J. Org. Chem. 2011, 7, 824–830, doi:10.3762/bjoc.7.94

• methodology, we demonstrated that the homoallylic amine products could be readily converted to synthetically useful building blocks, such as β-amino acids (Scheme 4). N-Boc-protection of the primary amine 12 followed by ozonolysis under Marshall’s conditions [40] yielded the β-amino acid derivative 24. The

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• complete inversion of stereochemistry, although no yield for this reaction was reported (Scheme 5). Peregrina and co-workers have developed a general method for the synthesis of α-functionalised β-amino acids [15][16][17] employing nucleophilic ring opening of cyclic sulfamidate 15 via an invertive SN2

• mechanism (Scheme 6) [16]. A variety of nucleophiles are capable of ring opening the sulfamidate 15 in good yields, and simple functional group transformations allow isolation of the functionalised β-amino acids. Sulfur-based nucleophiles generally undergo reaction with sulfamidate 15 cleanly to give

Photoinduced electron-transfer chemistry of the bielectrophoric N-phthaloyl derivatives of the amino acids tyrosine, histidine and tryptophan

• Axel G. Griesbeck,
• Jörg Neudörfl and
• Alan de Kiff

Beilstein J. Org. Chem. 2011, 7, 518–524, doi:10.3762/bjoc.7.60

• transfer product 2. On the other hand, phthaloyl derivatives of C-unprotected α-amino acids (e.g., derivatives of Gly, Ala, Val, Ile, Phe) undergo efficient photodecarboxylation to yield the corresponding amines, β-amino acids are converted to benzazepines, and γ-amino acids to benzopyrrolizidines (Scheme

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• low overall yields were observed including at the subsequent ester cleavage step (Scheme 17) [69]. In the well-known synthesis of benzolactam V8 (78) [70], Ma et al. proved the accelerating effect of α- (76) and β-amino acids (80) on aryl aminations (Scheme 18 and Scheme 19). Lotrafiban (SB-214857, 79

The C–F bond as a conformational tool in organic and biological chemistry

• Luke Hunter

Beilstein J. Org. Chem. 2010, 6, No. 38, doi:10.3762/bjoc.6.38

• adjacent hydroxyl group. The NOESY spectrum of 65 reveals no long-range interactions, suggesting that the crucial Tyr–Thr hydrogen bond is disrupted and that a linear peptide conformation is preferred. Fluorinated β-peptides β-Peptides are unnatural polymers composed of β-amino acids, which have an extra

2-Phenyl- tetrahydropyrimidine- 4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β²-amino acids

• Markus Nahrwold,
• Arvydas Stončius,
• Anna Penner,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2009, 5, No. 43, doi:10.3762/bjoc.5.43

• of stereocentres (SRS); Introduction Monosubstituted β-amino carboxylic acids can be classified according to their substitution pattern into α-substituted “β2-amino acids” and β-substituted “β3-amino acids” [1]. Oligomers of these β-amino acids are called “β-peptides” and tend to form distinct and

The oxanorbornene approach to 3-hydroxy, 3,4-dihydroxy and 3,4,5-trihydroxy derivatives of 2-aminocyclohexanecarboxylic acid

• Ishmael B. Masesane,
• Andrei S. Batsanov,
• Judith A. K. Howard,
• Raju Mondal and
• Patrick G. Steel

Beilstein J. Org. Chem. 2006, 2, No. 9, doi:10.1186/1860-5397-2-9

• -amino acids and this has been accompanied by the proliferation of procedures for their synthesis.[1] Much of the interest in these compounds emanate from the ability of oligomers or short polymers of cyclic β-amino acids to adopt well-defined secondary structures analogous to those of natural peptides

• . [2][3][4][5][6][7][8][9] Such oligomers therefore have a particular appeal for extending understanding of protein structure and stabilization. However, much of this work has focused on simple cyclic β-amino acids and analogous studies of substituted derivatives are less well developed. One reason for

• describe the stereoselective synthesis of further novel hydroxylated derivatives of ACHC using the exo nitro oxanorbornene adduct as the template. The basis of our approach to these poly hydroxylated cyclohexane β-amino acids was the recognition that the bicyclic oxanorbornene cycloadduct, derived from the