Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• -carboxylic acid was anchored to Wang resin and then subjected to the conditions for the alkenylation reaction with 2a using the solid catalyst (3 mg) for 48 h. After that, the reaction mixture was worked up, and the solid product was isolated and subjected to solid-state NMR spectroscopy. The results were

• then compared to, and found to be identical to, that for the indole-anchored Wang resin used as substrate for the reaction (Figures S16–S18, Supporting Information File 1). As a control experiment, the homogeneous alkenylation reaction of the Wang resin-anchored indole derivative was also carried out

• product was hydrolysed with aqueous NaOH, and the reaction mixture was then acidified with aqueous HCl to yield the product 5, which was characterised by spectroscopic techniques. The formation of the product 5 could be rationalised by the following: The C–H alkenylation reaction of the Wang resin

Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

• Sagnik Sengupta,
• Mena Asha Krishnan,
• Premansh Dudhe,
• Ramesh B. Reddy,
• Bishnubasu Giri,
• Sudeshna Chattopadhyay and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2018, 14, 2665–2679, doi:10.3762/bjoc.14.244

• segment [38] without fluorescent tag using Wang resin that is cleaved in strongly acidic conditions. Contrary to the aforementioned drawbacks, the present manuscript elicits a novel synthetic strategy for building new bioconstructs with several components in a continuous process without isolation of any

Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

• Bimal Koirala,
• Robert A. Hillman,
• Erin K. Tiwold,
• Michael A. Bertucci and
• Yftah Tal-Gan

Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151

• . All the CSP1 analogs were synthesized on a 4-benzyloxybenzyl alcohol (Wang) resin (0.65 mmol/g) pre-loaded with Fmoc-L-Lys(Boc). With the exception of the phenylglycine and norvaline derivatives, the CSP1 analogs were synthesized using standard Fmoc-based solid-phase peptide synthesis (SPPS

Position-dependent impact of hexafluoroleucine and trifluoroisoleucine on protease digestion

• Susanne Huhmann,
• Anne-Katrin Stegemann,
• Kristin Folmert,
• Damian Klemczak,
• Johann Moschner,
• Michelle Kube and
• Beate Koksch

Beilstein J. Org. Chem. 2017, 13, 2869–2882, doi:10.3762/bjoc.13.279

• show that upon smart design, these fluorinated amino acids can be used to engineer peptide drug candidates. Experimental Materials Fmoc-L-amino acids were purchased from ORPEGEN Peptide Chemicals GmbH (Heidelberg, Germany). Fmoc-Lys(Boc)Wang resin was from Novabiochem (Merck Chemicals GmbH, Darmstadt

• support by means of an Fmoc/tert-butyl protecting group strategy on a preloaded Fmoc-Lys(Boc)Wang resin (0.57 mmol/g loading) using 10 mL polypropylene reactors. HfLeu containing peptides were synthesized with an Activo-P11 automated peptide synthesizer (Activotec, Cambridge, United Kingdom). Couplings of

Peptide synthesis: ball-milling, in solution, or on solid support, what is the best strategy?

• Ophélie Maurin,
• Pascal Verdié,
• Gilles Subra,
• Frédéric Lamaty,
• Jean Martinez and
• Thomas-Xavier Métro

Beilstein J. Org. Chem. 2017, 13, 2087–2093, doi:10.3762/bjoc.13.206

• synthesis was conducted on an Fmoc-A-Wang resin on a 0.1 mmol scale with a 5-fold excess of Fmoc-protected amino acids solubilized in DMF (0.2 M), 0.5 M N,N′-diisopropylcarbodiimide in DMF (DIC, 5.0 equiv) as coupling reagent and 1 M Oxyma in DMF (5.0 equiv) as the coupling additive. Except for the coupling

Non-cross-linked polystyrene-supported 2-imidazolidinone chiral auxiliary: synthesis and application in asymmetric alkylation reactions

• Quynh Pham Bao Nguyen and
• Taek Hyeon Kim

Beilstein J. Org. Chem. 2013, 9, 2113–2119, doi:10.3762/bjoc.9.248

• , entry 4). Conclusion In summary, an NCPS-supported 2-imidazolidinone chiral auxiliary was developed with the following three clear advantages: (1) high loading capacity (more than 1.0–1.5 mmol/g loading of Wang resin or Merrifield resin), (2) remarkable solubility properties that are extremely useful

Parallel solid-phase synthesis of diaryltriazoles

• Matthias Wrobel,
• Jeffrey Aubé and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 1027–1036, doi:10.3762/bjoc.8.115

• Biology Center, 2121 Simons Drive, West Campus, Lawrence, KS 66047, USA 10.3762/bjoc.8.115 Abstract A series of substituted diaryltriazoles was prepared by a solid-phase-synthesis protocol using a modified Wang resin. The copper(I)- or ruthenium(II)-catalyzed 1,3-cycloaddition on the polymer bead allowed

• anhydrous DMF with sodium azide under heating. Coupling to Wang resin in dichloromethane, by using DIC and DMAP as coupling reagents, gave resin 7 in quantitative yield (Scheme 2) [18]. Commercially available 4-azidobenzoic acid (8) gave resin 9 in an analogous esterification of a Wang resin. Solid-phase

• synthesis of diaryltriazoles The conditions for the solid-phase synthesis of diaryltriazoles on functionalized Wang resin 7 were optimized by using five different alkynes 10a–e, containing acyclic or cyclic aliphatic moieties, simple arenes and 1-(but-3-yn-2-yl)-3-(4-chlorophenyl)-1-methylurea (10c) as an

Building photoswitchable 3,4'-AMPB peptides: Probing chemical ligation methods with reducible azobenzene thioesters

• Gehad Zeyat and
• Karola Rück-Braun

Beilstein J. Org. Chem. 2012, 8, 890–896, doi:10.3762/bjoc.8.101

• procedures (Supporting Information File 1) [4][17]. The syntheses of the auxiliary-linked glycine conjugates 7 and 8 were accomplished by using literature protocols developed by Dawson, Offer and MacMillan [7][8] (Figure 2). The Cys-peptide 3 and the Nα-auxiliary peptides 4 and 5 were assembled on Wang resin

• by manual Fmoc-based peptide synthesis using standard amino-acid building blocks (Scheme 2) [4]. Commercially available preloaded Wang resin was used, and HBTU was applied as the coupling reagent in the presence of DIPEA in NMP. Removal of the temporary Fmoc-protecting group was achieved by using 20

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• solid-phase synthesis of 5-aminopyrazoles 42 which were used as precursors for the preparation of pyrazolo[5,1-d][1,2,3,5]tetrazine-4(3H)-ones 43. Resin 39, obtained from Wang resin 38 and a 5-10 fold excess of 1,1′-carbonyldiimidazole (CDI), was treated with hydrazine hydrate in THF at room temperature

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• yield observed between each run and without the need for catalyst regeneration, providing 78% total yield of 14 with 88% ee. Cinchona alkaloid derivatives have been featured in a number of solid support-based continuous flow asymmetric reactions. For example, a Wang-resin supported quinine derivative

A practical synthesis of the ¹³C/¹⁵N- labelled tripeptide N-formyl- Met-Leu-Phe, useful as a reference in solid- state NMR spectroscopy

• Sven T. Breitung,
• Jakob J. Lopez,
• Gerd Dürner,
• Clemens Glaubitz,
• Michael W. Göbel and
• Marcel Suhartono

Beilstein J. Org. Chem. 2008, 4, No. 35, doi:10.3762/bjoc.4.35

• 13C/15N-labelled tripeptide 1 could be isolated in a typical batch. This peptide can be easily crystallised and is therefore well suited as a standard sample for setting up solid-state NMR experiments. Keywords: Fmoc solid phase peptide synthesis; formylation; f-MLF; magic-angle spinning; Wang resin

• . Results and Discussion Peptide Synthesis The synthesis of the MLF tripeptide started with the immobilisation of 13C/15N-labelled Fmoc-Phe-OH to the solid support (Wang resin 2). This esterification step, leading to 3 quantitatively, was performed by activating the COOH group with MSNT under mild reaction

• conditions for the removal of N-protective groups and the cleavage from the Wang resin [25]. Unintentional release of the growing peptide chain thus could be excluded. In addition, the use of liquid hydrogen fluoride is no longer required. Experimental General: All reagents were obtained from commercial