Synthesis of highly functionalized β-aminocyclopentanecarboxylate stereoisomers by reductive ring opening reaction of isoxazolines

• Melinda Nonn,
• Loránd Kiss,
• Reijo Sillanpää and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2012, 8, 100–106, doi:10.3762/bjoc.8.10

• cispentacin stereoisomer 2 into multifunctionalized β-amino acid derivative 12. Synthesis of multifunctionalized β-amino acid derivatives 13–16. Reaction conditions: NaBH4, NiCl2, Boc2O, EtOH/H2O, rt, 6 h. Acknowledgements We are grateful to the Hungarian Research Foundation (OTKA No. T81371) for financial

Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes

• Jan-Christoph Kehr,
• Douglas Gatte Picchi and
• Elke Dittmann

Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191

• the cyanobacterium Microcystis aeruginosa [17][18][19]. Microcystins are produced by different genera of freshwater cyanobacteria and inhibit eukaryotic protein phosphatases of types 1 and 2A. A signature of this heptapeptide family is the unusual β-amino acid Adda (3-amino-9-methoxy-2,6,8-trimethyl

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

• cyclic amine 19 was subjected to analogous reaction conditions to form the tetrahydrofuran β-amino acid derivative 26. Conclusion We have developed a method for the one-pot simultaneous hydrozirconation of allenes and nitriles to yield allylic zirconocenes and N-zirconoimines, respectively. These

• to depend on the allene substitution. The intramolecular variant of this reaction was used to prepare 3-aminotetrahydrofurans and 3-aminotetrahydropyrans, and these addition products can subsequently be transformed into synthetically valuable β-amino acid building blocks. Coupling constant analysis

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

• a variety of thiols to a range of nitroalkenes 49 proceeds to give 50 and hence 51 in good yield and good enantioselectivity (Scheme 19). α-Arylthio-β-amino acid 54 was prepared from Michael adduct 52 in three steps (Scheme 20) in good yield and with full conservation of enantiomeric purity. Palomo

• of enone 46. Organocatalytic conjugate addition to nitroalkenes 49. Preparation of β-amino acid 54. Sulfur migration within oxazolidine-2-thiones 56. Preparation of thiols 62 by self-regeneration of stereocentres. Synthesis of (5R)-thiolactomycin. Preparation of tertiary thiols and thioethers via α

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• of glucagon release. Consequently, insulin secretion increases leading to decreased blood glucose levels in diabetes type II patients. Structurally, this novel antihyperglycaemic consists of a fluorinated β-amino acid which is coupled to a trifluoromethylated triazolopiperazine (Scheme 55). In SAR

α,β-Aziridinylphosphonates by lithium amide-induced phosphonyl migration from nitrogen to carbon in terminal aziridines

• David. M. Hodgson and
• Zhaoqing Xu

Beilstein J. Org. Chem. 2010, 6, 978–983, doi:10.3762/bjoc.6.110

• an entry to a biologically important β-amino acid mimic class. Aziridines 1h–j. Proposed aziridinyl anion induced N- to C-phosphonyl migration. Selected previously observed N- to C-phosphorous migrations [17][18][21]. Partial N- to C-migration with N-diphenylphosphinylaziridine 10 [24]. Synthesis and

Oxalyl retro-peptide gelators. Synthesis, gelation properties and stereochemical effects

• Janja Makarević,
• Milan Jokić,
• Leo Frkanec,
• Vesna Čaplar,
• Nataša Šijaković Vujičić and
• Mladen Žinić

Beilstein J. Org. Chem. 2010, 6, 945–959, doi:10.3762/bjoc.6.106

• centers are denoted corresponding to that of oxalamide α- and β-amino acid, respectively, as depicted in Scheme 1). Compared to the previously studied bis(amino acid)-oxalamide gelators (Figure 1), the retro-dipeptidic gelators, in addition to the oxalamide hydrogen bonding unit, also contain two peptidic

Synthesis of glycosylated β³-homo-threonine conjugates for mucin-like glycopeptide antigen analogues

• Florian Karch and
• Anja Hoffmann-Röder

Beilstein J. Org. Chem. 2010, 6, No. 47, doi:10.3762/bjoc.6.47

• carbohydrate antigens (TACA) have proven to be important target structures for the development of molecularly defined anti-cancer vaccines. The strategic incorporation of β-amino acid building blocks into such mucin-type sequences offers the potential to create pseudo-glycopeptide antigens with improved

• α/β-peptides adopt stable secondary structures closely related to those of natural α-peptides [21][22]. Moreover, inclusion of a single β-amino acid into an α-peptidic sequence already augments local and/or general stability against proteolytic degradation in vitro and in vivo; thus enabling the

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

• . This concept is elegantly illustrated by the diastereoisomeric β-peptides 66 and 67 (Figure 18) [56]. The β-amino acid sequence of 66 and 67 is known to promote the formation of a left-handed helix and this helical conformation can be either reinforced or destabilised by a fluorine substituent. In the

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

• , Universitätsstr. 25, 33615 Bielefeld, Germany 10.3762/bjoc.5.43 Abstract Novel procedures have been developed to condense benzaldehyde effectively with β-amino acid amides to cyclic benzyl aminals. Double carbamate protection of the heterocycle resulted in fully protected chiral β-alanine derivatives. These

• , this structural modification would facilitate a final release of the β2-amino acid by hydrogenolysis of all remaining benzyl-type N-protective groups. Results and Discussion Cyclocondensation of benzaldehyde and β-amino acid amides to 2-phenyl-tetrahydropyrimidine-4(1H)-ones is problematic, since

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

• afforded the trans β-amino acid derivative 22 as established by NMR experiments. Having prepared the 4,5-cis diol, we turned our attention to the synthesis of the corresponding trans diols. These could be prepared by simple hydrolytic cleavage of epoxides 10–13. In line with this plan, treatment of 12 with