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

• halogenated by unique biochemical mechanisms through the two non-heme iron(II)-dependent halogenases BarB1 and BarB2 (Figure 6A) [40]. Further extraordinary features of the pathway include one-carbon truncation during chain elongation, E-double bond formation and thiazole ring formation. Jamaicamide The

• -type monooxygenases encoded by the cluster, HctG or HctH, to 2,3-dihydroxyisovaleric acid. Two other NRPS modules contain all the required domains for adenylation and heterocyclization of cysteine, and an FMN-dependent oxidase domain, which is likely involved in thiazole ring formation. The cluster

• first ribosomal pathway discovered was the biosynthesis of patellamides in the symbiotic cyanobacterium Prochloron. The cyclic octapeptides are pseudosymmetric and contain thiazole and oxazolin rings. Patellamides 16 are typically moderately cytotoxic, and some variants were further reported to reverse

Functionalization of heterocyclic compounds using polyfunctional magnesium and zinc reagents

• Paul Knochel,
• Matthias A. Schade,
• Sebastian Bernhardt,
• Georg Manolikakes,
• Albrecht Metzger,
• Fabian M. Piller,
• Christoph J. Rohbogner and
• Marc Mosrin

Beilstein J. Org. Chem. 2011, 7, 1261–1277, doi:10.3762/bjoc.7.147

• obtained in 63% yield. Also, the dibromothiazole 19 allows insertion of zinc only into the most labile C–Br bond (in position 2) leading to the zincated thiazole 20. After Negishi cross-coupling [10][11][12], the 2-arylated thiazole 21 is obtained in 85% yield. Polar functional groups, such as a tosyloxy

The Eschenmoser coupling reaction under continuous-flow conditions

• Sukhdeep Singh,
• J. Michael Köhler,
• Andreas Schober and
• G. Alexander Groß

Beilstein J. Org. Chem. 2011, 7, 1164–1172, doi:10.3762/bjoc.7.135

• sulfide contraction but rather the thiazole formation to 13 took place exclusively (Scheme 3) [19]. The thiazol formation by condensation is a well known side reaction of the sulfide contraction. Nevertheless, and in contrast to the batch reaction, no thiazole formation was observed under the investigated

Chiral gold(I) vs chiral silver complexes as catalysts for the enantioselective synthesis of the second generation GSK-hepatitis C virus inhibitor

• María Martín-Rodríguez,
• Carmen Nájera,
• José M. Sansano,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2011, 7, 988–996, doi:10.3762/bjoc.7.111

• origin of the enantioselectivity of the chiral gold(I) catalyst was justified according to DFT calculations, the stabilizing coulombic interaction between the nitrogen atom of the thiazole moiety and one of the gold atoms being crucial. Keywords: BINAP; 1,3-dipolar cycloaddition; gold; HCV

• antiviral agents [6][7]. In further studies, a second generation of antiviral agents 2 and 3 (Figure 1), offering a greater dynamic range even for HCV genotype 1b, was published [5][8][9]. These molecules incorporated a 2-thiazole heterocycle instead of the 2-thienyl group, together with a more hydrophobic

• )-5b is 23.4 kcal mol−1, which means that the process is feasible at the reaction temperature. It is worth noting that there is a stabilizing coulombic interaction between the nitrogen atom of the thiazole moiety (N7) and one of the gold atoms of the catalyst, both in the TS and the ylide complex. This

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

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

• kcal·mol−1 stabilization. For example, the thiazole derivative 148 was reacted with CF3SO3H and then benzene to give two products (151 and 152, Scheme 30) [42]. When the two precursor superelectrophiles are studied computationally (B3LYP 6-311(d,p) level), the charge separated 1,4-dication 150 is estimated

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• trifluoromethylated arenes by treatment with Umemoto reagents, 5a or 5b, in the presence of Pd(OAc)2 and Cu(OAc)2 at 110 °C in a mixture of dichloroethane (DCE) and 10 equiv of trifluoroacetic acid (TFA). Arenes having other heterocycles such as thiazole, imidazole, or pyrimidine also reacted under the same

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

• Nernstian response (58.1 mV/decade) in the range 5 × 10−6–10−1 M ammonium ion activity, reflecting a similar detection limit as nonactin. Similarly, Kim et al. investigated the use of a thiazole containing dibenzo-18-crown-6 derivative (12) as an ammonium ionophore (Figure 8) in an ISE sensor and reported a

Synthetic incorporation of Nile Blue into DNA using 2′-deoxyriboside substitutes: Representative comparison of (R)- and (S)-aminopropanediol as an acyclic linker

• Daniel Lachmann,
• Sina Berndl,
• Otto S. Wolfbeis and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2010, 6, No. 13, doi:10.3762/bjoc.6.13

• nucleic acids (TINA) [27][28], and by our group for fluorescent DNA base substitutions by ethidium [29][30], indole [31][32], thiazole orange [33][34], perylene bisimide [35][36] and phenothiazine [37]. This 2′-deoxyriboside substitution provides high chemical stability and conformational flexibility for

• we have shown with indole [32] and thiazole orange [33][34]. DMT-protected (R)-3-amino-1,2-propanediol 1 as a precursor was synthesized according to literature [29][43]. The hydroxy function of commercially available 2-propyn-1-ol was converted into an activated ester by 1,1′-carbonyldiimidazole and

Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules

• Matthias Lehmann and
• Jens Seltmann

Beilstein J. Org. Chem. 2009, 5, No. 73, doi:10.3762/bjoc.5.73

• pyridyl or acceptor substituted aromatic unit at the periphery of the molecule [23][24]. Fluorenone [25], oxadiazole [26], thiazole and thiadiazole [24] derivatives have been synthesised and evidence for biaxiality in their monotropic nematic phases has been presented. Monotropic phases are metastable and

Synthesis and enzymatic evaluation of 2- and 4-aminothiazole- based inhibitors of neuronal nitric oxide synthase

• Graham R. Lawton,
• Haitao Ji,
• Pavel Martásek,
• Linda J. Roman and
• Richard B. Silverman

Beilstein J. Org. Chem. 2009, 5, No. 28, doi:10.3762/bjoc.5.28

• equivalent of acid, which was sufficient to cleave the Boc group. Buffering the reaction resulted in incomplete conversion to the thiazole because acidic conditions are necessary to catalyze the final dehydration step in the reaction [17]. However, the problem was solved by simply neutralizing the mixture on

• does not need to be diprotected to allow the Mitsunobu reaction with phthalimide as the nucleophile to proceed (28a-c). This is presumably because the thiazole nitrogen is less nucleophilic. Cleavage of the phthalimide group gave amines 29a-c. The syntheses of 4a-c were completed by reductive amination

• . Nonetheless, the synthetic methodology is useful for the construction of this ring system. 4-Aminothiazole-based inhibitors with various alkyl groups at the thiazole 5-position could be synthesized, but proved to be unstable in aqueous medium. This is a valuable insight for others contemplating this ring

Enantiospecific synthesis of [2.2]paracyclophane- 4-thiol and derivatives

• Gareth J. Rowlands and
• Richard J. Seacome

Beilstein J. Org. Chem. 2009, 5, No. 9, doi:10.3762/bjoc.5.9

• amino sulfide (Rp)-9. Simultaneous sulfide deprotection and thiazole formation was achieved by treating (Rp)-9 with concentrated hydrochloric acid, paraformaldehyde and pyridine [48]. Although the yield of (Rp)-10 is not yet satisfactory, it shows the potential of our methodology for the formation of

• ) 8.89 (1H, s, thiazole CH), 6.81 (1H, d, J = 7.5 Hz, H-13), 6.68 (1H, d, J = 7.5 Hz, H-12), 6.52 (1H, d, J = 8.0 Hz, H-16), 6.46 (1H, d, J = 7.5 Hz, H-15), 6.18 (1H, d, J = 7.5 Hz, H-7), 5.85 (1H, d, J = 7.5 Hz, H-8), 3.99–3.93 (1H, m, H-2 endo), 3.27–3.21 (1H, m, H-1 endo), 3.17–3.11 (1H, m, H-9 endo