Flow microreactor synthesis in organo-fluorine chemistry

• Hideki Amii,
• Aiichiro Nagaki and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2013, 9, 2793–2802, doi:10.3762/bjoc.9.314

• [18F]-radiolabeled molecular imaging probes. Flow microreactor synthesis of dipeptides. Flow synthesis involving SNAr reactions. Flow synthesis of fluoroquinolone antibiotics. Highly controlled formation of PFPMgBr. Selective flow synthesis of photochromic diarylethenes. Flow microreactor system for

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• cocatalyst. It was postulated that Zn(OAc)2 facilitates the conversion of the initially formed amine radical cation to the imine 65a and subsequently activates the imine for nucelophilic attack. N-arylglycine esters and N-arylglycine derived dipeptides worked quite well under these conditions. However, the

The conjugation of nonsteroidal anti-inflammatory drugs (NSAID) to small peptides for generating multifunctional supramolecular nanofibers/hydrogels

• Jiayang Li,
• Yi Kuang,
• Junfeng Shi,
• Yuan Gao,
• Jie Zhou and
• Bing Xu

Beilstein J. Org. Chem. 2013, 9, 908–917, doi:10.3762/bjoc.9.104

• acetylsalicylic acid (aspirin) to connect with dipeptides results in a compound hydrolyzing easily at the ester bond of aspirin, we use salicylic acid (Sal) instead to conjugate with diphenylalanine and dialanine (AA) to make compounds 5a and 5g, respectively. Self-assembly and hydrogelation After the synthesis

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• aldol reaction between solid substrates (1b and 2a). (S)-Binam-L-prolinamide catalysed asymmetric aldol reaction by using a ball-mill. aConversion. Asymmetric aldol reaction assisted by ball-milling catalysed by dipeptides (A) with III and (B) with IV. Thiodipeptide-catalysed asymmetric aldol reaction

Asymmetric synthesis of γ-chloro-α,β-diamino- and β,γ-aziridino-α-aminoacylpyrrolidines and -piperidines via stereoselective Mannich-type additions of N-(diphenylmethylene)glycinamides across α-chloro-N-sulfinylimines

• Gert Callebaut,
• Sven Mangelinckx,
• Pieter Van der Veken,
• Karl W. Törnroos,
• Koen Augustyns and
• Norbert De Kimpe

Beilstein J. Org. Chem. 2012, 8, 2124–2131, doi:10.3762/bjoc.8.239

• specifically cleave off N-terminal dipeptides and are involved in the degradation of incretin hormones, including glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). GLP-1 is involved in the regulation of glucose homeostasis through stimulation of insulin secretion

Enantioselective supramolecular devices in the gas phase. Resorcin[4]arene as a model system

• Caterina Fraschetti,
• Matthias C. Letzel,
• Antonello Filippi,
• Maurizio Speranza and
• Jochen Mattay

Beilstein J. Org. Chem. 2012, 8, 539–550, doi:10.3762/bjoc.8.62

• achiral subunits forming a chiral macrocyclic scaffold. Chiral centers in the side chains Flexible peptidoresorcin[4]arenes as chiral selectors of dipeptides. In 2002, the first investigations of chiral recognition by calixarenes in the gas phase were carried out in Rome by the group of Prof. Speranza by

• )-(−)-2-butylamine (B) (Equation 5 and Equation 6) was monitored. In addition to the displacement enantioselectivity, the structural analogies between the resorcinarene and the dipeptides made other evaluations possible as, for instance, the effect of the –R in the CO2R groups of the host and the guest

• protonated “hook” for dipeptides [43]. Indeed, the reaction enantioselectivity factors reflect these differences ([M∙H∙G]+ (M = I–III): ρ < 1; [IV∙H∙G]+slow: ρ ≥ 1). Based on the NMR measurements [44], in which the homochiral [M∙H∙G]+ complexes appear to be more stable than the heterochiral ones, a ρ < 1

Asymmetric synthesis of quaternary aryl amino acid derivatives via a three-component aryne coupling reaction

• Elizabeth P. Jones,
• Peter Jones,
• Andrew J. P. White and
• Anthony G. M. Barrett

Beilstein J. Org. Chem. 2011, 7, 1570–1576, doi:10.3762/bjoc.7.185

• . Hydrolysis of the sterically less hindered adducts gave the corresponding quaternary amino acids with no racemization, whereas hydrolytic ring opening gave the corresponding valine dipeptides from bulkier bislactims. Keywords: aryl amino acids; arynes; asymmetric; multicomponent; quaternary; Introduction

• the relatively less bulky products, 6a, 6d and 6e, was subjected to standard, mild hydrolysis conditions, employing 0.5 M HCl in THF at room temperature [12], affording the desired quaternary methyl esters as their corresponding dipeptides, 8a, 8d and 8e, in good yields (Scheme 7). The less shielded

• underwent hydrolysis to the corresponding valine dipeptides. NOESY correlation observed for 6a. X-ray crystal structure of 6b. Transition state analysis to explain the lack of diastereoselectivity at C-2. 3-Component coupling reactions of arynes. E+ = electrophile. Aryne mediated α-arylation of amino acids

Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• , Schwarz and Wandrey developed a cascade of two membrane reactors for the production of dipeptides [35]. In the first reactor carboxypeptidase Y (CPD-Y) catalyzes the condensation between the ester 36 and the amide 37 of two amino acids (Scheme 12). Deamidation of the resulting dipeptide-amide 38 proceeds

Synthesis of enantiomerically enriched (R)-¹³C-labelled 2-aminoisobutyric acid (Aib) by conformational memory in the alkylation of a derivative of L-alanine

• Stephen P. Fletcher,
• Jordi Solà,
• Dean Holt,
• Robert A. Brown and
• Jonathan Clayden

Beilstein J. Org. Chem. 2011, 7, 1304–1309, doi:10.3762/bjoc.7.152

• formation of pairs of diastereoisomeric dipeptides from small aliquots of 6* with an excess of Cbz-L-Phe, EDC and HOBt (Scheme 2). The ratio of diastereoisomers was determined by comparison of the peak heights of the two 13C signals by 13C NMR (Figure 2). As shown in Table 1, the d.r. of 7 (and hence the

Multicomponent synthesis of artificial nucleases and their RNase and DNase activity

• Anton V. Gulevich,
• Lyudmila S. Koroleva,
• Olga V. Morozova,
• Valentina N. Bakhvalova,
• Vladimir N. Silnikov and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2011, 7, 1135–1140, doi:10.3762/bjoc.7.131

• due to their lower cytotoxicity and elevated potential penetration into living eukaryotic cells. Moreover, a few dipeptides [12] were shown to induce interferon production, thus providing antivirus defence. Therefore, the development of new peptidomimetics with ribonuclease activity is an important

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

• -assembly motifs, chirality effects and morphological characteristics of gels formed by chiral retro-dipeptidic gelators in the form of terminal diacids (1a–5a) and their dimethyl ester (1b–5b) and dicarboxamide (1c–5c) derivatives. Terminal free acid retro-dipeptides (S,S)-bis(LeuLeu) 1a, (S,S)-bis(PhgPhg

• possessing advanced properties and functions [5][6][7][8][9][10]. It has been shown that even short peptides, such as dipeptides, tripeptides or tetrapeptides, themselves or incorporated into more complex structures, are capable of self-assembling into fibers or fibrils [11][12][13][14][15]. In a number of

• with those of (S,S)-1b/(R,R)-1b and (S,R)-1b/(R,S)-1b racemic mixtures (Scheme 1). Gelation properties Terminal diacid retro-dipeptides Gelation observed for selected gelator–solvent pairs is expressed by gelator effectiveness (Geff, mL) corresponding to the maximal volume of solvent that could be

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

• response. Unprotected dipeptides showed an affinity to compound 44 if amino groups were present within a suitable distance, for example, as found in dipeptides with a C-terminal Lys. Lys-Lys (Kass = 1020 M−1) and Gly-Lys (Kass = 930 M−1) showed the highest affinity constants in methanol/water 10:1 [184

Synthesis and binding studies of two new macrocyclic receptors for the stereoselective recognition of dipeptides

• Ana Maria Castilla,
• M. Morgan Conn and
• Pablo Ballester

Beilstein J. Org. Chem. 2010, 6, No. 5, doi:10.3762/bjoc.6.5

• experiments are used to quantify the dimerization constants, as well as the association constant values of the 1:1 complexes formed between the receptors and a series of diamides and dipeptides. The receptors show moderate levels of selectivity in the molecular recognition of the hydrogen-bonding pattern

• -DL) = −1.08 kcal/mol and ΔΔG01 (DD-LD) = −0.89 kcal/mol). Surprisingly, the linear synthetic precursors show higher levels of stereoselectivity than their cyclic counterparts. Keywords: dipeptides; host–guest; macrocyclic; molecular recognition; receptors; stereoselective; Introduction Manipulation

• take place during vancomycin action, but also because the structures of the most efficient receptors prepared might be useful as scaffolds for future antibiotics. Herein, we report the design and synthesis of two new macrocyclic receptors, 1 and 2, conceived for the binding of dipeptides, in particular