Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• coating, where they properly helped to melt and cure the applied powder monomers nearly just in one step [16]. Typical monomers used in CtP, liquid coatings and powder coatings derive from urethane (meth)acrylates, epoxy (meth)acrylates, polyester(meth)acrylates or polyether (meth)acrylates. Literature

An anomalous addition of chlorosulfonyl isocyanate to a carbonyl group: the synthesis of ((3aS,7aR,E)-2-ethyl-3-oxo-2,3,3a,4,7,7a-hexahydro-1H-isoindol-1-ylidene)sulfamoyl chloride

• Aytekin Köse,
• Aslı Ünal,
• Ertan Şahin,
• Uğur Bozkaya and
• Yunus Kara

Beilstein J. Org. Chem. 2019, 15, 931–936, doi:10.3762/bjoc.15.89

• ] contribute to the formation of a stable structure (Figure 2a and Figure 2b). Based on the structure of the product, we propose the reaction mechanism shown in Scheme 4. First, CSI reacts with the carbonyl carbon in the imide ring to form a four-membered urethane ring. Afterwards the imine is formed by the

Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

• Antonella Di Vincenzo,
• Antonio Palumbo Piccionello,
• Alberto Spinella,
• Delia Chillura Martino,
• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• characteristic -N3 stretching band at 2103 cm−1. Interestingly, spectra show also a band at ca. 1688 cm−1, in a position consistent with the presence of a urethane carbonyl group. The latter finding provides a confirmation of the formation of oxazinanone derivatives shown in Scheme 4. On passing to NMR

• signal at 154.4 ppm that confirms the presence of the urethane carbonyl group. All these attributions were confirmed by analysis of COSY and HMQC 2D spectra (Supporting Information File 1, Figures S3 and S4). The NMR spectra of mixture II (see Supporting Information File 1, Figures S5–S8) show similar

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• tetraoxaadamantanes. Inward-pointing isocyanate, urethane and carbamate groups in bisdioxines. The diisocyanate is obtained by Curtius and Hofmann rearrangements of the diazides and diamides [38][39]. Microwave-assisted tetraoxaadamantane formation. Cyclic bisdioxine ester derivative 34 forming a single mono

Detection of therapeutic radiation in three-dimensions

• John A. Adamovics

Beilstein J. Org. Chem. 2017, 13, 1325–1331, doi:10.3762/bjoc.13.129

• adventitious moisture with the diisocyanate. The degree of hardness of the dosimeter can be contolled by the type of polyol and catalyst utilized. Hardness ranging from rigid to tissue-like can be achieved [46]. The urethane reaction also tolerates up to relatively high addition (50%) of various solvents such

New syntheses of (±)-tashiromine and (±)-epitashiromine via enaminone intermediates

• Darren L. Riley,
• Joseph P. Michael and
• Charles B. de Koning

Beilstein J. Org. Chem. 2016, 12, 2609–2613, doi:10.3762/bjoc.12.256

• approach most commonly comprise a nitrogen atom in a pyrrolidine or piperidine ring conjugated at C-2 through an exocyclic vinyl fragment to an ester (vinylogous urethane) or another electron-withdrawing substituent (usually ketone, nitrile, nitro or sulfone). When suitable carbon chains bearing terminal

• for the vinylogous urethane 8b agreed with those for the same compound which we had previously prepared by alternative methods [13][14]. For comparison, Table 1 also includes our previously reported results [19] with an α-bromo Weinreb acetamide, 2-bromo-N-methoxy-N-methylacetamide. A key step in the

• iodine under refluxing conditions [30]. The products from vinylogous urethane 8b and vinylogous cyanamide 8c were easily purified under standard chromatographic conditions, affording the corresponding bicyclic systems 9b and 9c in 59% and 72% yields, respectively (Scheme 2 and Table 1). We had previously

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

• coupled with cyclization to create the cyclic carbonate 5, the homopolymer could be self-deactivated due to competing hydrogen-bond interactions of the urethane carbonyl group with neighboring groups. Since the comonomer should act as diluting agent a better access of the carbonyl group to the bromo

Diastereoselective Ugi reaction of chiral 1,3-aminoalcohols derived from an organocatalytic Mannich reaction

• Samantha Caputo,
• Andrea Basso,
• Lisa Moni,
• Renata Riva,
• Valeria Rocca and
• Luca Banfi

Beilstein J. Org. Chem. 2016, 12, 139–143, doi:10.3762/bjoc.12.15

• , by additional crystallization, affording these key intermediates in high ee and de (syn relative configuration, see Supporting Information File 1). The tert-butyl urethane was then deblocked with trifluoroacetic acid. Neutralization and extraction afforded crude aminoalcohols 5a–e, that were directly

Preparation of Pickering emulsions through interfacial adsorption by soft cyclodextrin nanogels

• Shintaro Kawano,
• Toshiyuki Kida,
• Mitsuru Akashi,
• Hirofumi Sato,
• Motohiro Shizuma and
• Daisuke Ono

Beilstein J. Org. Chem. 2015, 11, 2355–2364, doi:10.3762/bjoc.11.257

• . We have previously reported urethane-crosslinked CD polymers, which were prepared by reacting heptakis(2,6-di-O-methyl)-β-cyclodextrins (DM-β-CDs) with aromatic diisocyanates such as 4,4’-methylenebis(phenyl isocyanate) (MDI) and 1,4-phenylene diisocyanate (PDI) [18]. Although MDI- or PDI-crosslinked

• ultrasonication. Previously, we prepared a urethane-crosslinked DM-β-CD/PDI polymer at a higher crosslinker/DM-β-CD feed ratio (>5.0). The resulting polymer forms a submicrometer-sized particle and does not disperse in water [18]. These results reveal that controlling the crosslinking degree gives a polymer with

• the phenyl groups in PDC to the peaks of H1 protons of DM-β-CD indicates that the PDC/DM-β-CD ratio is two. The appearance of C=O stretching bands from urethane (1714 cm−1) in the FTIR spectrum (Supporting Information File 1, Figure S1) confirms that a urethane-crosslinked polymer is formed. In

Urethane tetrathiafulvalene derivatives: synthesis, self-assembly and electrochemical properties

• Xiang Sun,
• Guoqiao Lai,
• Zhifang Li,
• Yuwen Ma,
• Xiao Yuan,
• Yongjia Shen and
• Chengyun Wang

Beilstein J. Org. Chem. 2015, 11, 2343–2349, doi:10.3762/bjoc.11.255

• Technology of Ministry of Education, Hangzhou Normal University, Hangzhou 310012, China 10.3762/bjoc.11.255 Abstract This paper reports the self-assembly of two new tetrathiafulvalene (TTF) derivatives that contain one or two urethane groups. The formation of nanoribbons was evidenced by scanning electron

• microscopy (SEM) and X-ray diffraction (XRD), which showed that the self-assembly ability of T1 was better than that of T2. The results revealed that more urethane groups in a molecule did not necessarily instigate self-assembly. UV–vis and FTIR spectra were measured to explore noncovalent interactions. The

• driving forces for self-assembly of TTF derivatives were mainly hydrogen bond interactions and π–π stacking interactions. The electronic conductivity of the T1 and T2 films was tested by a four-probe method. Keywords: hydrogen bond; nanoribbon; self-assembly; tetrathiafulvalene; urethane; Introduction

Convenient preparation of high molecular weight poly(dimethylsiloxane) using thermally latent NHC-catalysis: a structure-activity correlation

• Stefan Naumann,
• Johannes Klein,
• Dongren Wang and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 2261–2266, doi:10.3762/bjoc.11.246

• range of accessible monomer structures has grown impressively [6][7]. Nowadays, NHC-mediated polymerization can be applied to prepare polymers of high industrial and commercial importance, such as poly(amide)s [8][9], poly(ether)s [10], poly(urethane)s [11][12] or poly(acrylate)s [13][14][15][16][17][18

Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

• Kazuaki Kato,
• Daisuke Matsui,
• Koichi Mayumi and
• Kohzo Ito

Beilstein J. Org. Chem. 2015, 11, 2194–2201, doi:10.3762/bjoc.11.238

• process was repeated again followed by drying to yield acryloyl modified polyrotaxane (Acryl-PR, 5.41 g) as a white solid: 1H NMR (400 MHz, DMSO-d6, 343 K): 7.0 (NH of urethane), 6.3, 5.9 (CH2 of vinyl), 6.1 (CH of vinyl), 4.9 (C(1)H of CD), 4.1 (C(=O)O-CH2), 3.5 (PEG), 3.2 (-CH2-NH). Synthesis of

• evaporation. 1H NMR (400 MHz, DMSO-d6, 343 K): 7.0 (NH of urethane), 6.3, 5.9 (CH2 of vinyl), 6.1 (CH of vinyl), 4.9 (C(1)H of CD), 4.1 (C(=O)O-CH2), 3.8 (SiO-CH2), 3.5 (PEG), 3.2 (-CH2-NH), 2.3 (OC(=O)-CH2), 1.1 (SiOCH2-CH3), 1.0 (Si-CH2). Synthesis of silica nanocomposite polyrotaxane gels 1.5 mL of DMSO

The preparation of new functionalized [2.2]paracyclophane derivatives with N-containing functional groups

• Henning Hopf,
• Swaminathan Vijay Narayanan and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 437–445, doi:10.3762/bjoc.11.50

• Information File 1). Finally, when 16 was first refluxed in ethanol and the resulting solution (presumably containing the corresponding bis(urethane) is subsequently treated with an aqueous solution of potassium hydroxide (20%), 4,12-diamino[2.2]paracyclophane (8) was obtained in quantitative yield. Since we

• , however, furnish the corresponding pseudo-para-crownophane, but provided a dark brown intractable material. Changing the trapping agent for 16 to butane-1,4-diol (toluene, reflux, 20 h) led to bis(urethane diol) 20 (43%). In the hope that this would react with a second equivalent of 16 and yield the

• with the bis secondary amine 23, the latter in acceptable yields. Although it was not tested specifically, it is likely that 22 is the precursor for 23. We assume that the reduction of 18 starts as usual by attack of hydride at the urethane carbonyl group. Because of the inherent strain in the

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

• ][3][11] paves the way for the synthesis of many other types of compounds with hairpin turns and parallel pendant chains. Experimental General Preparations of the di(hexylurea) 4, the di(ethyl urethane) 5 and the diamides 7 were carried out as previously described [1][11][12][13]. Crystallography

Synthesis of a resin monomer-soluble polyrotaxane crosslinker containing cleavable end groups

• Ji-Hun Seo,
• Shino Nakagawa,
• Koichiro Hirata and
• Nobuhiko Yui

Beilstein J. Org. Chem. 2014, 10, 2623–2629, doi:10.3762/bjoc.10.274

• per α-CD molecule was completely soluble in conventional resin monomers such as 2-hydroxyethyl methacrylate (HEMA) and urethane dimethacrylate (UDMA). The synthesized n-butyl-containing PRX was further modified with 2-aminoethyl methacrylate to provide crosslinkable acrylic groups onto PRX. The

• dentistry [18]. The rapid polymerization of acrylic groups with crosslinkable dimethacrylate monomers such as triethyleneglycol dimethacrylate (TEGDMA) or urethane dimethacrylate (UDMA), and the high permeability of the resin monomers to dental tissue have been suggested as optimal properties to develop

• methacrylate hydrochloride, N,N’-carbonyldiimidazole, ethyl 4-(dimethylamino)benzoate (DMBE), 3,5-di-tert-butyl-4-hydroxytoluene (BHT) and 2-hydroxyethyl methacrylate were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Urethane methacrylate (Art ResinTM) was purchased from Negami Chemical

Substitution effect and effect of axle’s flexibility at (pseudo-)rotaxanes

• Friedrich Malberg,
• Jan Gerit Brandenburg,
• Werner Reckien,
• Oldamur Hollóczki,
• Stefan Grimme and
• Barbara Kirchner

Beilstein J. Org. Chem. 2014, 10, 1299–1307, doi:10.3762/bjoc.10.131

• low-barrier molecular rotary motors with rotaxane architecture [24]. The co-conformational selectivity of two dibenzo-24-crown-8 macrocycles to ammonia binding sites in a [3]rotaxane [25], and the hydrogen bonding strength in polymeric urethane rotaxanes in a mean-field model [26] were investigated by

Intermediates in monensin biosynthesis: A late step in biosynthesis of the polyether ionophore monensin is crucial for the integrity of cation binding

• Wolfgang Hüttel,
• Jonathan B. Spencer and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 361–368, doi:10.3762/bjoc.10.34

• semisynthetic urethane derivatives of monensin A show maintained or even improved antibacterial activity [37][38][39]. The recently-determined crystal structure of the C-26-O-phenylurethane of monensin A sodium salt shows that although one of the carboxylate oxygen atoms coordinates the cation, this atom is

• also engaged in hydrogen bonding to the secondary alcohol borne at C-25, while the other carboxylate atom is engaged in an H-bond to the NH group of the urethane, thus maintaining the stability of the pseudocyclic structure [39]. The very different metal coordination pattern seen in dehydroxymonensin A

Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

• Jie Zhang,
• Hong-Kui Zhang and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2013, 9, 2358–2366, doi:10.3762/bjoc.9.271

• -benzyloxycarbonyl group imposed A1,3-strain on piperidine derivatives founded the basis for the observed stereocontrol. Thus, we chose keto-lactam 10 as our substrate. Although compound 10 is not a urethane, and a A1,3-strain not longer exists, a simple chair conformational-controlled preferential equatorial attack

Establishing the concept of aza-[3 + 3] annulations using enones as a key expansion of this unified strategy in alkaloid synthesis

• Aleksey I. Gerasyuto,
• Zhi-Xiong Ma,
• Grant S. Buchanan and
• Richard P. Hsung

Beilstein J. Org. Chem. 2013, 9, 1170–1178, doi:10.3762/bjoc.9.131

• . Retrosynthetically, we envisioned propyleine (12) to come from the decarboxylation reaction of vinylogous carbamic acid 15 [10][28], which could be derived from stereoselective hydrogenation of the endocyclic olefin in tricycle 16 (Scheme 4). Vinylogous urethane 16 should be accessible via our intramolecular aza-[3

• + 3] annulation of enone 17. Enone 17 could be E or Z with respect to the vinylogous urethane olefin, and cis or trans with respect to the enone double bond. Thus, from the spectroscopic analysis stand point, synthesis of 17 could be messy. In the forward direction to synthesize 17, we used the

• by condensation with Meldrum’s acid in the presence of Ni(acac)2. Treatment of 23 with MeONa in MeOH under reflux gave vinylogous urethane 24. It is noteworthy that the geometry of the vinylogous urethane double bond exclusively favored Z, presumably due to the internal hydrogen bonding. Cleavage of

Partial thioamide scan on the lipopeptaibiotic trichogin GA IV. Effects on folding and bioactivity

• Marta De Zotti,
• Barbara Biondi,
• Cristina Peggion,
• Matteo De Poli,
• Haleh Fathi,
• Simona Oancea,
• Claudio Toniolo and
• Fernando Formaggio

Beilstein J. Org. Chem. 2012, 8, 1161–1171, doi:10.3762/bjoc.8.129

• Lawesson's reagent [53], we decided to select the longest segment of our sequences, which, in principle, could permit complete regioselectivity between the peptide bond to be thionated and the other peptide bonds (in addition to the known regioselectivity versus the urethane and ester bonds) [53][54][55][56

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• miniemulsion. For example, castor oil (a triol) has been used as the monomer [102]. Li et al. showed that short diols can be also replaced efficiently by poly(tetramethylene glycol) [103]. The polyaddition reaction to form urethane bonds was also carried out with a cyclodextrin derivative and IPDI as the

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

• -urethane), 144.0, 143.8 (Fmoc-C1a, Fmoc-C8a), 141.3, 141.3 (Fmoc-C4a, Fmoc-C5a), 127.4 (Fmoc-C3, Fmoc-C6), 126.8, 126.7 (Fmoc-C2, Fmoc-C7), 124.7, 124.6 (Fmoc-C1, Fmoc-C8), 119.6, 119.5 (Fmoc-C4, Fmoc-C5), 99.1 (GalNAc-C1), 77.6 (hTγ), 68.3 (GalNAc-C3), 67.4 (GalNAc-C4), 66.6 (GalNAc-C5), 65.9 (Fmoc-CH2

• , 170.1 (C=O), 157.1 (C=O-urethane), 144.0, 143.9 (Fmoc-C1a, Fmoc-C8a), 141.2 (Fmoc-C4a, Fmoc-C5a), 127.4 (Fmoc-C3, Fmoc-C6), 126.8, 126.7 (Fmoc-C2, Fmoc-C7), 124.9 (Fmoc-C1, Fmoc-C8), 119.5 (Fmoc-C4, Fmoc-C5), 98.6 (GalNAc-C1), 77.5 (hTγ), 69.0 (GalNAc-C3), 67.7 (GalNAc-C4), 66.8 (GalNAc-C5), 66.4 (Fmoc

• , hTα), 2.55 (dd, 1 H, J = 8.7 Hz, 15.6 Hz, hTα), 2.17, 2.15, 2.06, 2.06, 2.05, 2.04, 1.97 (7s, 21 H, 6 × CH3-Ac, CH3-AcNH), 1.22 (d, 3 H, J = 6.6 Hz, hTδ); 13C NMR (101 MHz, DEPT, HSQC, CD3OD), δ (ppm) = 174.7, 173.0, 172.5, 172.2, 171.6, 171.2 (C=O), 158.5 (C=O-urethane), 145.5, 145.3 (Fmoc-C1a, Fmoc

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl- 5-pentyloctahydroindolizine (8-epi-indolizidine 209B) and [(1S,4R,9aS)-(−)-4-pentyloctahydro- 2H-quinolizin- 1-yl]methanol

• Joseph P. Michael,
• Claudia Accone,
• Charles B. de Koning and
• Christiaan W. van der Westhuyzen

Beilstein J. Org. Chem. 2008, 4, No. 5, doi:10.1186/1860-5397-4-5

• was then effected by first treating the thiolactam with ethyl bromoacetate, after which reaction of the resulting S-alkylated intermediate with triethyl phosphite and triethylamine in acetonitrile gave the vinylogous urethane (+)-28 in 75% yield. At this stage, however, our fears of the discrepant

• bromoacetate followed by treatment with triphenylphosphine and triethylamine in acetonitrile give the vinylogous urethane (+)-38 in 80% yield. Hydrolysis of the acetate with potassium carbonate in methanol then afforded the pivotal alcohol (+)-29 (70%). The scene was now set for cyclisation to the

• (−)-39 in 70% yield. In order to introduce the remaining stereogenic centres of the target system, the alkene bond of the bicyclic vinylogous urethane 39 needs to be reduced stereoselectively. Based on our previous success with the indolizidine analogue 19, we opted for catalytic hydrogenation, which is

Flexible synthetic routes to poison- frog alkaloids of the 5,8-disubstituted indolizidine- class I: synthesis of common lactam chiral building blocks and application to the synthesis of (-)-203A, (-)-205A, and (-)-219F

• Naoki Toyooka,
• Dejun Zhou,
• Hideo Nemoto,
• H. Martin Garraffo,
• Thomas F. Spande and
• John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 29, doi:10.1186/1860-5397-3-29

• protected hydroxymethyl side-chain (Figure 2). The synthesis began with the known piperidone 3, [15] which was treated with n-BuLi and then CbzCl to provide the Cbz-urethane 4. Treatment of 4 with LiHMDS followed by 2-[N,N-bis(trifluoromethylsulfonyl)amino]-5-chloropyridine (Comins' reagent) [16] gave the