A new class of organogelators based on triphenylmethyl derivatives of primary alcohols: hydrophobic interactions alone can mediate gelation

• Wangkhem P. Singh and
• Rajkumar S. Singh

Beilstein J. Org. Chem. 2017, 13, 138–149, doi:10.3762/bjoc.13.17

• coordination, ionic, hydrophobic forces, etc.) into the gelator molecular structure and studying their gelation behaviour. H-bonding interaction (present in amide, urea, carbamate linkages, etc) alone or in combination with other interactions is the most extensively used strategy in the design of gelators [23

Solution-phase automated synthesis of an α-amino aldehyde as a versatile intermediate

• Hisashi Masui,
• Sae Yosugi,
• Shinichiro Fuse and
• Takashi Takahashi

Beilstein J. Org. Chem. 2017, 13, 106–110, doi:10.3762/bjoc.13.13

• manually concentrated in vacuo. The obtained residue was purified manually using silica gel column chromatography. Carbamate 2a was obtained in 82% yield. Acetal formation was also demonstrated using ChemKonzert. A solution of substrate 2a in dichloromethane was stirred at 25 °C in the reaction vessel (RF1

Robust C–C bonded porous networks with chemically designed functionalities for improved CO₂ capture from flue gas

• Damien Thirion,
• Joo S. Lee,
• Ercan Özdemir and
• Cafer T. Yavuz

Beilstein J. Org. Chem. 2016, 12, 2274–2279, doi:10.3762/bjoc.12.220

• high regeneration energy and raises the overall cost of the carbon capture operations [12][25]. Dry CO2 uptake is not always meaningful, especially with amine functionalities, as flue gas from power plants contains moisture [26]. When binding to CO2, amines go through either carbamate or carbamic acid

p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• are highly reactive compounds that are usually treated with alcohols or amines to give either a new carbonate or a carbamate-linked compound depending on the nucleophile. In one of our earlier reports, polycarbamate nucleic acids were synthesized from p-nitrophenyl carbonates with amines of nucleic

• ] and the synthesis of carbamate-linked compounds using p-nitrophenyl carbonates, we herein report our results from nucleophilic ring opening reactions of DBU and DBN using p-nitrophenyl carbonates. Results and Discussion In the course of this study, we observed that in the absence of a nucleophile the

• in the solvent, leading to the ring opening and formation of the corresponding caprolactam carbamates (Scheme 1). The structure of 1b was confirmed by 1H and 13C spectroscopy, which showed the characteristic carbamate NH triplet at 5.80 ppm in the 1H NMR spectrum and the expected peaks at 176.6 and

Stereodynamic tetrahydrobiisoindole “NU-BIPHEP(O)”s: functionalization, rotational barriers and non-covalent interactions

• Golo Storch,
• Sebastian Pallmann,
• Frank Rominger and
• Oliver Trapp

Beilstein J. Org. Chem. 2016, 12, 1453–1458, doi:10.3762/bjoc.12.141

• crucial. In contrast to 1a and 1b, three coexisting isomeric species were observed with NMR spectroscopy in CDCl3 for tetrahydrobiisoindole “NU-BIPHEP(O)” 1c. This behaviour originates from an increased interconversion barrier between the E/Z isomers of the carbamate N–C(O) unit that is derived from a

• carbamate selector units that are soluble in organic solvents [27][28][29][30]. We prepared cellulose derivative 4 which bears 5-fluoro-2-methylphenylcarbamate binding sites [27] and investigated the formation of diastereomeric adducts with 1b and 3 by 31P{1H} NMR spectroscopy in anhydrous CDCl3

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• , carbamate 138, hexahydrobenzothiophene 140 and benzothiophene 142 were converted to the corresponding bisphosphonates 139, 141 and 143, respectively (Scheme 30). The synthesized heterocyclic bisphosphonates showed anti-inflammatory properties. 3 Knoevenagel-induced domino reactions An efficient method into

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• prepared from 3-chloropivaloyl chloride (3) by amide formation and subsequent cyclization with the Burgess reagent (methyl N-(triethylammoniumsulfonyl)carbamate) using standard procedures (Scheme 2). Subsequent nucleophilic substitution with KPP2 in refluxing THF proved to be much faster than the analogous

Gold-catalyzed direct alkynylation of tryptophan in peptides using TIPS-EBX

• Gergely L. Tolnai,
• Jonathan P. Brand and
• Jerome Waser

Beilstein J. Org. Chem. 2016, 12, 745–749, doi:10.3762/bjoc.12.74

• , a carbamate and an amide protecting group. A promising result was obtained with 5 mol % gold chloride as catalyst at room temperature in acetonitrile (Table 1, entry 1). Although the reaction did not go to completion even after two days, the desired C2 alkynylation product 5a was obtained in 44

Antibiotics from predatory bacteria

• Juliane Korp,
• María S. Vela Gurovic and
• Markus Nett

Beilstein J. Org. Chem. 2016, 12, 594–607, doi:10.3762/bjoc.12.58

• manifests in the so-called western side chain, which ranges from 10 (myxopyronin A) up to 18 carbon atoms (corallopyronin B). In contrast, the eastern chain is conserved among all members and features a terminal methyl carbamate moiety. Differences in the architectures of the respective biosynthetic

cis–trans-Amide isomerism of the 3,4-dehydroproline residue, the ‘unpuckered’ proline

• Vladimir Kubyshkin and
• Nediljko Budisa

Beilstein J. Org. Chem. 2016, 12, 589–593, doi:10.3762/bjoc.12.57

• the carbamate groups as C(=O)–O–H···O=C(–Ot-Bu)–N. The same has been recently reported in particular in the cases of N-Boc-2-methylproline [41] and N-Boc 4,5-difluoromethanoproline [42]. In the crystal structure the ring conformations were found to be: twisted endo-pucker for 5, exo-pucker for 7, and

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• this work, Shi, Li and co-workers partnered the isatin derived N-Boc ketimines 8 with MVK (6, Scheme 3a) to obtain the corresponding adducts 9 with very good selectivity [22]. Interestingly, replacing the Boc group with an ethyl carbamate decreased the yield and enantioselectivity dramatically, as did

Mycothiol synthesis by an anomerization reaction through endocyclic cleavage

• Shino Manabe and
• Yukishige Ito

Beilstein J. Org. Chem. 2016, 12, 328–333, doi:10.3762/bjoc.12.35

• pyranosides with N-acetyl 2,3-trans-carbamate groups exhibited complete anomerization from β-glycoside to α-glycoside in the presence of a weak Lewis acid through an endocyclic cleavage reaction [29][30][31][32][33]. We showed evidence of the endocyclic cleavage reaction by trapping linear cations through

• reduction, and intramolecular Friedel–Crafts reaction [29][30] (Scheme 2). In particular, the reaction of pyranosides bearing acetyl substituents on the carbamate groups showed complete anomerization [32]. We expected that anomerization via endocyclic cleavage would be useful for mycothiol synthesis

• phthalimide group in the 2-position, was converted to α-glycoside 4, by introducing an N-acetyl 2,3-trans-carbamate group (Scheme 3) and by conducting an anomerization reaction. The glycosylation reaction of phthalimido-protected glucosamine thioglycoside 5 with inositol 6 [24] afforded β-linked pseudo

Amino-functionalized (meth)acryl polymers by use of a solvent-polarity sensitive protecting group (Br-t-BOC)

• Helmut Ritter,
• Monir Tabatabai and
• Markus Herrmann

Beilstein J. Org. Chem. 2016, 12, 245–252, doi:10.3762/bjoc.12.26

• attempted to replace one methyl group with a phenyl substituent simply by the reaction of 1a with 1-bromo-2-phenylpropan-2-ol (2b). Although spectroscopic examinations gave evidence for the successful formation of the expected carbamate 3c, only the corresponding amine hydrobromide 4a was isolated as main

Asymmetric α-amination of β-keto esters using a guanidine–bisurea bifunctional organocatalyst

• Minami Odagi,
• Yoshiharu Yamamoto and
• Kazuo Nagasawa

Beilstein J. Org. Chem. 2016, 12, 198–203, doi:10.3762/bjoc.12.22

• requirement of bifunctionality in catalyst 1, we performed the α-amination reaction in the presence of carbamate 9 or triurea 10 as a catalyst (Scheme 2). In both cases, the enantioselectivity of the α-amination product 3a was drastically decreased. These results clearly show that the guanidine and urea

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275

• either FeTPA (1 mol %) or FeBPMEN (10 mol %) converts cyclohexene to the allylic hydroxylamine (tert-butyl cyclohex-2-en-1-yl(hydroxy)carbamate) in moderate yields. Spectroscopic studies and trapping experiments suggest the reaction proceeds via a nitroso–ene mechanism, with involvement of a free N-Boc

• hydroxylamine 9 alongside the Fenton oxidation products alcohol 10 and ketone 11 [53], and a small amount of tert-butyl carbamate (12, Scheme 1). Initial reactions under an argon or air atmosphere returned product mixtures in the ratios shown in Table 1. Under an argon atmosphere, the allylic hydroxylamine 9

Diversity-oriented synthesis of analogues of the novel macrocyclic peptide FR-225497 through late stage functionalization

• Jyotiprasad Mukherjee,
• Suman Sil and
• Shital Kumar Chattopadhyay

Beilstein J. Org. Chem. 2015, 11, 2487–2492, doi:10.3762/bjoc.11.270

• solution phase peptide coupling between L-Phe-D-Pro-OMe (6) (prepared by hydrogenolysis of the corresponding carbamate 5) and L-Cbz-Phe-OH (7) followed by elaboration of the resulting tripeptide 8 via N-terminus deprotection leading to 9 followed by a second peptide coupling of the latter with the known

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• able to disrupt the cholesterol-rich lipid envelope and inactivate viral invasion [17]. Cholesterol-based hydrazones exhibited insecticidal activity against the larval stage of Mythimna separate (Walker) [18]. Cholesterol–carbamate conjugates, for instance (3β)-cholest-5-en-3-yl (2-aminoethyl)carbamate

Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides

• Armando Navarro-Vázquez

Beilstein J. Org. Chem. 2015, 11, 1441–1446, doi:10.3762/bjoc.11.156

• position. A final and more demanding test is the Hsung observation that whereas only ynamide 12 was observed upon isomerization of the corresponding N-propargylamide, the related carbamate 13 only evolves to the allenamide stage [18]. Furthermore, urea 14 (see page 5069 of [3], we thank one of the referees

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• protective groups at the amino and carboxy termini of the amino acid (resulting in carbamate and/or ester protective groups) [4], as well as for the subsequent side-chain acylation. Relevant examples are too numerous to render possible any exhaustive or useful listing herein, but use of modern computerized

Molecular cleft or tweezer compounds derived from trioxabicyclo[3.3.1]nonadiene diisocyanate and diacid dichloride

• Gert Kollenz,
• Ralf Smounig,
• Ferdinand Belaj,
• David Kvaskoff and
• Curt Wentrup

Beilstein J. Org. Chem. 2015, 11, 1–8, doi:10.3762/bjoc.11.1

• the diisocyanate 1, viz. the di(hexylurea) 4 and the di(methyl carbamate) 5, as well as the calculated structures of diamide derivatives 7. Results and Discussion Diurea and dicarbamate The di(hexylurea) 4 and the di(methyl carbamate) 5 were synthesized by addition of hexylamine and methanol

• a dashed line (H(N82–O90) = 2.006 Å). Stereoscopic ORTEP plot of the di(methyl carbamate) 5 showing the atomic numbering scheme. The ellipsoids are drawn at the 50% probability level. The H atoms bonded to N are drawn with arbitrary radii; the H atoms of the methyl groups were omitted for reasons of

• . Calculated structure of 7b-a (B3LYP/6-31G**). For other conformers (7b-b and 7b-c) and full details, see Supporting Information File 1. Ring opening taking place on attempted optimization of the calculated, putative endo,exo isomer of 1. Synthesis of the di(hexylurea) and di(methyl carbamate) derivatives 4

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• electrochemical anodic oxidation of an α-methylene group to an amide (or carbamate) to generate a new carbon–carbon bond via an anodic methoxylation step and Lewis acid mediated generation of an N-acyliminium ion reactive intermediate; Scheme 1 overviews such a process [11]. Although the anodic oxidation

• conditions [32][33]. Although the introduction of an electroauxiliary requires an additional synthetic step to prepare, the resulting carbon–tin, carbon–silicon or carbon–sulfur bond has a less positive oxidation potential than an unfunctionalised carbamate. Therefore, exquisite control can be exerted on the

• is attached either to the carbamate or amide (Figure 5) [69][70][71] (using a platinum anode and tungsten cathode electrochemical set-up) [69] or the use of Cu-PyBox chiral ligand systems [72]. The cation pool method can be adapted to a multicomponent reaction (MCR) when an N-acyliminium ion is

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• depicted in Scheme 14 and Scheme 15) [58][59][60]. PhI(OCH2CF3)2 was generated anodically from iodobenzene in a solution of LiClO4 in 2,2,2-trifluoroethanol and served as reagent for the oxidative intramolecular coupling of phenyl rings with amide or carbamate groups. With control experiments the authors

• with different substituents on the aromatic ring and on the alkynyl group were cyclized in good to excellent yields. When N-ethoxycarbonyl-substituted anilines are converted under the conditions described above, the carbamate group is cleaved and unprotected indoles are obtained. An electrochemical

• dienophile is facilitated. Yoshida, Suga and co-workers reported on the use of electrogenerated N-acyliminium ions as heterodienes in [4 + 2] cycloadditions [66]. It was found that these highly reactive species, generated from silylated carbamate 57 at −78 °C (cation pool method), undergo cycloaddition at 0

Encapsulation of biocides by cyclodextrins: toward synergistic effects against pathogens

• Véronique Nardello-Rataj and
• Loïc Leclercq

Beilstein J. Org. Chem. 2014, 10, 2603–2622, doi:10.3762/bjoc.10.273

• complexation, all organic biocides developed in the following sections also present an enhancement of their water-solubility in addition to the other benefits highlighted. The methyl N-(1H-benzimidazol-2-yl)carbamate (named carbendazim, see Figure 1) was used to illustrate the effect of CDs on its aqueous

• the methyl carbamate residue is the binding site. Despite the weak binding constants, the carbendazim water-solubility is increased but the effect remains low (1.9-fold compared to free carbendazim in the presence of 15 mM of β-CD). In 2012, Ge et al. proposed to use the HP-β-CD to enhance the

• bioavailability of biocides. As an example, Szejtli et al. reported that the biocidal activity of methyl [1-(butylcarbamoyl)benzimidazol-2-yl]carbamate (named benomyl) can be improved in the presence of β-CD (Scheme 2) [46]. Indeed, the same fungicidal efficiency can thus be achieved with a lower active

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• R1 and R2. In both cases, a second electron reduction in presence of CO2 yields a carboxylate intermediate with an additional carbonate or carbamate group. The latter is converted to the corresponding α-hydroxy acid or to an α-amino acid after acid hydrolysis in the product work-up [75][76][77]. An

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions

• Anne-Katrin Späte,
• Verena F. Schart,
• Julia Häfner,
• Andrea Niederwieser,
• Thomas U. Mayer and
• Valentin Wittmann

Beilstein J. Org. Chem. 2014, 10, 2235–2242, doi:10.3762/bjoc.10.232

• Diels–Alder reaction between methylcyclopropene tags and tetrazines has become a popular ligation reaction due to the small size and high reactivity of cyclopropene tags. Attaching the cyclopropene tag to mannosamine via a carbamate linkage has made the reaction even more efficient. Here, we expand the

• (4) [23] (Figure 1) to label sialic acid residues on the surface of living cells via MOE. Since carbamate-linked methylcyclopropenes have significantly higher reaction rates in DAinv reactions with tetrazines [22][28], we recently introduced Ac4ManNCyoc (3) as a derivative for rapid labeling of

• metabolically engineered cell-surface sialic acids [24]. The application of 3 was prompted by the previous observation that carbamate-modified ManNAc derivatives are also accepted in the biosynthetic pathway [19][29]. Derivative 3 in combination with a sulfo-Cy3-tetrazine conjugate enabled dual sugar labeling