Enhancing the reactivity of 1,2-diphospholes in cycloaddition reactions

• Almaz Zagidullin,
• Vasili Miluykov,
• Elena Oshchepkova,
• Artem Tufatullin,
• Olga Kataeva and
• Oleg Sinyashin

Beilstein J. Org. Chem. 2015, 11, 169–173, doi:10.3762/bjoc.11.17

• , phosphinidenes, etc. [2]. At the same time, the presence of electron-withdrawing substituents (cyano-, alkoxy-, or halo-) at the phosphorus atom reduces the aromaticity of the monophosphole ring and facilitates cycloaddition reactions resulting in novel 7-phosphanorbornenes [5][6], which was verified by

Multicomponent versus domino reactions: One-pot free-radical synthesis of β-amino-ethers and β-amino-alcohols

• Bianca Rossi,
• Nadia Pastori,
• Simona Prosperini and
• Carlo Punta

Beilstein J. Org. Chem. 2015, 11, 66–73, doi:10.3762/bjoc.11.10

• the corresponding alkoxy radical (Scheme 4, reaction 4). The latter undergoes hydrogen abstraction from the C–H bond of THF in the α-position of the oxygen (Scheme 4, reaction 5). This promotes the formation of a carbon-centered nucleophilic radical, which in turn quickly adds to the activated carbon

Mono- and multilayers of molecular spoked carbazole wheels on graphite

• Stefan-S. Jester,
• A. Vikas Aggarwal,
• Daniel Kalle and
• Sigurd Höger

Beilstein J. Org. Chem. 2014, 10, 2783–2788, doi:10.3762/bjoc.10.295

• ]. These represent basic building blocks for a supramolecular Archimedean surface tessellation system [9]. Thereby, the highly oriented pyrolytic graphite (HOPG) acts as a template along the main axis directions of which the alkyl/alkoxy side chains align [10][11], and consequently the superstructures can

• solvent, octanoic acid (OA), which has also previously been used for imaging MSWs [2][4]. We compared the so-obtained images of MSW 2 with its precursor 1 under similar conditions. In all images, regions covered with conjugated backbones and alkoxy side chains are observed in bright and dark colors

• the HOPG main axes (and alkoxy side chain alignment directions) [10][11], d1. A high resolution STM image is shown in Figure 2c, and a molecular model is superimposed to a copy of the image in Figure 2d. On a first sight, a bright hexagonal frameline (corresponding to the six rim segments) is observed

Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism

• Joscha Vollmeyer,
• Friederike Eberhagen,
• Sigurd Höger and
• Stefan-S. Jester

Beilstein J. Org. Chem. 2014, 10, 2774–2782, doi:10.3762/bjoc.10.294

• –alkynylene macrocycles are promising candidates as future mounts for functional units. These are separated from each other and cannot interact intermolecularly if the rings are adsorbed in parallel to the substrate. The exterior of the macrocycles can be substituted with alkyl side chains (or their alkoxy

• 2D superstructures are not predictable [17] or show a conformational polymorphism [18], also as an effect of varying compound concentrations in the supernatant solution [19][20]. A recent approach investigating macrocycles of triangular, quadratic, pentagonal, and hexagonal shapes that carry alkoxy

• side chains pointing away in normal direction from their sides has led to the concept of molecular polygons [4]. An example for the schematic design of an alkoxy side chain substituted molecular hexagon and its characteristic side-chain interdigitation concept are shown in Figure 2a and b, respectively

Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test

• Gerald Jarre,
• Steffen Heyer,
• Elisabeth Memmel,
• Thomas Meinhardt and
• Anke Krueger

Beilstein J. Org. Chem. 2014, 10, 2729–2737, doi:10.3762/bjoc.10.288

• observed surface loading for 13 is higher due to secondary reactions of already grafted alkoxy silanes [5]. In a first series of experiments the assay was carried out on nanodiamond samples 5 and 15 using the protocol reported by Troll et al. [22]. Surprisingly, very low values for the amino group loading

N–O Cleavage reactions of heterobicycloalkene-fused 2-isoxazolines

• Jaipal R. Nagireddy,
• Geoffrey K. Tranmer,
• Emily Carlson and
• William Tam

Beilstein J. Org. Chem. 2014, 10, 2200–2205, doi:10.3762/bjoc.10.227

• coordination of AlCl3 to the alkoxy oxygen of 24 prevents retro-aldol cleavage from taking place. Finally, in a manner analogous to our former proposal, hydrolysis ensues to produce 16 (Scheme 4). Conclusion To conclude, we have demonstrated the first examples of Raney nickel/AlCl3-mediated cleavage reactions

Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

• Mahesh K. Lakshman,
• Manish K. Singh,
• Mukesh Kumar,
• Raghu Ram Chamala,
• Vijayender R. Yedulla,
• Domenick Wagner,
• Evan Leung,
• Lijia Yang,
• Asha Matin and
• Sadia Ahmad

Beilstein J. Org. Chem. 2014, 10, 1919–1932, doi:10.3762/bjoc.10.200

• formation. However, a previously undescribed reaction of these compounds with alcohols in the presence of a base, leads to 1-alkoxy-1H-benzo- (Bt-OR) and 7-azabenzotriazoles (At-OR). Although BOP undergoes reactions with alcohols to furnish 1-alkoxy-1H-benzotriazoles, Bt-OTs proved to be superior. Both

• , primary and secondary alcohols undergo reaction under generally mild reaction conditions. Correspondingly, 1-alkoxy-1H-7-azabenzotriazoles were synthesized from At-OTs. Mechanistically, there are three pathways by which these peptide-coupling agents can react with alcohols. From 31P{1H}, [18O]-labeling

• ][1,2,3]triazole, via in situ formation of pyrrolidine enamines and Pd catalysis. Keywords: alkoxy; azabenzotriazole; benzotriazole; peptide-coupling; phosphonium; Introduction Benzotriazole derivatives are of importance in diverse contexts. As examples, in medicinal chemistry substituted benzotriazoles

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• preferred for all calculated oxazines. In the reactions of diazo esters with 5-alkoxy-substituted isoxazoles 1f,h, in contrast to isoxazoles 1a–e, no formation of 1,3-oxazines was detected. Instead, the corresponding 1-oxa-5-azahexa-1,3,5-trienes 4a–f were isolated in moderate to good yields (Table 3). The

• structures of compounds 4a–f were verified by 1H, 13C NMR, IR spectroscopy, and HRMS. Furthermore, the structures of compounds 4a,b were confirmed by X-ray analysis (Figure 4). According to 1H NMR no corresponding 1,3-oxazines were formed. Thus, only reactions of carbenoids with 5-alkoxy-substituted

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• attributed in part to the missing α-orientated 4-alkoxy substituent present in sanfetrinem (113), which may act as a potential leaving group and appears to be crucial for activity [97]. Anthoplalone (1999) Isolated from the Okinawan actinian Anthopleura pacifica, anthoplalone (8) is a secosesquiterpene with

Synthesis of new, highly luminescent bis(2,2’-bithiophen-5-yl) substituted 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole

• Anastasia S. Kostyuchenko,
• Vyacheslav L.Yurpalov,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2014, 10, 1596–1602, doi:10.3762/bjoc.10.165

• synthetic approach towards the preparation of functionalised, soluble, donor–acceptor (DA) alkylbithiophene derivatives of oxadiazole, thiadiazole and triazole is reported. Taking advantage of the Fiesselmann reaction, reactive bithiophene synthons having alkyl or alkoxy substituents at designated positions

• their extended conjugation and frequently have to be rendered soluble by introducing long alkyl- or alkoxy-type side substituents. This functionalisation opens up an additional route to modifying their redox, electronic and optical properties by using side substituents with different electron accepting

• derivatives 13 and 14, is caused by the electron-donating alkoxy chain, increasing the molecule HOMO level resulting in narrowing of the frontier orbital gap. For the three targets with invariant bithiophene units (18, 13 and 15), the smallest absorption band energy is observerd for 15, i.e., the compound

Synthesis of a sucrose dimer with enone tether; a study on its functionalization

• Zbigniew Pakulski,
• Norbert Gajda,
• Magdalena Jawiczuk,
• Jadwiga Frelek,
• Piotr Cmoch and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2014, 10, 1246–1254, doi:10.3762/bjoc.10.124

• structure 13 could be assigned on the basis of the Kishi rule [26] (Scheme 2). It postulates that the attack of OsO4 occurs from the side opposite to hydroxy (alkoxy) substituent(s) flanking the double bond. Since in 12, both alkoxy units act in the same direction, very high diastereoselectivity is not

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp²)–H activation/C–O formation

• Seohyun Shin,
• Dongjin Kang,
• Woo Hyung Jeon and
• Phil Ho Lee

Beilstein J. Org. Chem. 2014, 10, 1220–1227, doi:10.3762/bjoc.10.120

• -catalyzed C(sp2 and sp3)–H activation/C–O formation [42]. In this context, we herein report the synthetic method of alkoxy dibenzooxaphosphorin oxides from 2-(aryl)arylphosphonic acid monoesters via Pd-catalyzed C(sp2)–H activation/C–O formation (Scheme 1). Results and Discussion First, a wide range of 2

• . Synthesis of alkoxy dibenzooxaphosphorin oxides by C(sp2)–H activation/C–O formation. Preparation of 2-(aryl)arylphosphonic acid monoethyl esters. A variety of organic acids and monoprotected amino acids as ligands. Cyclization of 2-arylphenylphosphonic acid monoethyl esters. Cyclization of 2-(aryl

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• vinylhalide substrates 75a were cross-coupled with diphenylphosphine or diphenyltrimethylsilylphosphine. When diphenylphosphine was used, triethylamine was added for the basic activation of the phosphinating agent. All the tested substrates 75a contained an alkoxy or amino group and depending on their

• position relative to the halogen, it was necessary to adjust the reaction temperature. The substrates bearing the halogen in the α-position to the alkoxy or amino group proved to be more reactive. With the halogen in β-position the substrate was less activated and the temperature had to be raised. Method B

Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative

• Bernd Schmidt and
• Sylvia Hauke

Beilstein J. Org. Chem. 2014, 10, 1023–1031, doi:10.3762/bjoc.10.102

• better results were obtained with two different phosphine free catalysts comprising a hemilabile alkoxy substituted benzylidene ligand, even at only moderately elevated temperatures. The acrolein cross metathesis product can be converted into the 4-benzoate of L-amicetose via benzoylation, Pd-catalyzed

Use of activated enol ethers in the synthesis of pyrazoles: reactions with hydrazine and a study of pyrazole tautomerism

• Denisa Tarabová,
• Stanislava Šoralová,
• Martin Breza,
• Marek Fronc,
• Wolfgang Holzer and
• Viktor Milata

Beilstein J. Org. Chem. 2014, 10, 752–760, doi:10.3762/bjoc.10.70

• ethers are reactive species frequently used in organic synthesis [1]. They react predominantly with electrophiles. The introduction of one or more strong electron-withdrawing groups at the other end of the double bond from the alkoxy group causes an inversion of electron demand. These activated enol

• synthesis [20] (8 h heated under reflux in toluene 55% yield or 2 h in CHCl3) in 69% yield. Other preparations of 5d were carried out in aqueous media [21][22][23]. Enol ethers with different alkoxy groups afforded the same products. Reactions were carried out in ethanol or without a solvent. If the ratio

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• substituted 1,2-dihydroisoquinolines 40 characterized by the presence of an α-hydroxy/alkoxy-α-carboxylate carbon pendant. The oxonium ylide 39 was prepared by a well-known procedure involving a rhodium carbenoid intermediate, generated in situ from the corresponding diazoacetate 37 under Rh2(OAc)4 catalysis

An oxidative amidation and heterocyclization approach for the synthesis of β-carbolines and dihydroeudistomin Y

• Suresh Babu Meruva,
• Akula Raghunadh,
• Raghavendra Rao Kamaraju,
• U. K. Syam Kumar and
• P. K. Dubey

Beilstein J. Org. Chem. 2014, 10, 471–480, doi:10.3762/bjoc.10.45

• ), 127.8, 127.8, 126.0 (2C), 121.3, 118.5, 117.9, 111.5, 108.4, 75.6 (alkoxy carbon), 38.3, 25.2. HRMS (EI) m/z: [M]+ calcd for C18H17N2O2, 293.1290; found, 293.1333; HRMS of dehydrated 8a (EI) m/z: [M]+ calcd for C18H15N2O, 275.1184; found, 275.1220. (2,9-Dihydro-1H-pyrido[3,4-b]indol-1-yl)(p-tolyl

The Flögel-three-component reaction with dicarboxylic acids – an approach to bis(β-alkoxy-β-ketoenamides) for the synthesis of complex pyridine and pyrimidine derivatives

• Mrinal K. Bera,
• Moisés Domínguez,
• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 394–404, doi:10.3762/bjoc.10.37

• ][26][27][28][29][30][31][32][33], in particular by MCRs, is of permanent high interest. In the course of exploring the reactivity of alkoxyallenes and their utilization as C-3 building blocks [34][35][36][37] our group developed a highly flexible method to synthesize β-alkoxy-β-ketoenamides of type 1

• – discovered and mechanistically elucidated by Oliver Flögel – features a three-component reaction that employs alkoxyallenes, nitriles and carboxylic acids: upon treatment with n-butyllithium the allene is lithiated in α-position to the alkoxy moiety; the addition of a nitrile as electrophile to this highly

• reactive nucleophile results in the formation of an iminoallene adduct [38] that is protonated and subsequently acylated by the addition of a carboxylic acid furnishing a β-alkoxy-β-ketoenamide 1. A detailed mechanistic proposal for this reaction has been disclosed in previous reports [38][39]. Our earlier

Efficient carbon-Ferrier rearrangement on glycals mediated by ceric ammonium nitrate: Application to the synthesis of 2-deoxy-2-amino-C-glycoside

• Alafia A. Ansari,
• Y. Suman Reddy and
• Yashwant D. Vankar

Beilstein J. Org. Chem. 2014, 10, 300–306, doi:10.3762/bjoc.10.27

• position so that the C-allyl pseudoglycoside is fomed. However, we were not able to isolate Me3SiOAc. As the acetate ion and the acetyl radical are better leaving groups the formation of the acyl radical seems to be more facile than the formation of the alkoxy radicals (e.g., benzyloxy and methoxy). This

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• presence of Yb(fod)3 to afford 2-alkoxy-3,4-dihydro-5-vinyl-2H-pyran 33. In the presence of electron-poor dienophiles, as N-phenylmaleimide, maleic anhydride, activated azo compounds or naphthoquinone, 33 underwent normal Diels–Alder reactions thus giving the corresponding cycloadducts 34 as single

• -phenylmaleimide and 4-phenyltriazoline-3,5-dione. Asymmetric synthesis of a α-hydroxyalkylcyclohexane. Tandem [4 + 2]-cycloaddition/allylboration of 3-silyloxy- and 4-alkoxy-dienyl boronates. Metal-mediated cycloisomerization/Diels–Alder reaction/allylboration sequence. Cobalt-catalyzed Diels–Alder/allylboration

Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• , only the starting material could be reisolated. Encouraged by these findings we attempted to perform the [3,3]-sigmatropic rearrangement with C1-substituted A rings, as many B-seco limonoids are oxygenated at this position. For this purpose, both the anti- and syn-substituted β-alkoxy esters 56 and 57

• were synthesized (Scheme 7; for experimental procedure see Supporting Information File 1). In the literature [50] not many examples are known in which β-alkoxy esters serve as rearrangement precursors as the β-elimination of the alkoxy group can easily occur under the rearrangement conditions. Indeed

• revealed that the main product is 1S-configurated as in most B-seco limonoids suggesting that an equatorial attack of the hydride is slightly preferred over the axial attack. However bearing in mind the elimination issues with β-alkoxy esters during Ireland–Claisen rearrangements discussed above we decided

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• by a Rupe rearrangement [190] using refluxing acetic acid as solvent to give ketone 220. Addition of deprotonated ketone 220 onto acryloylsilane 221 [191] gave alkoxy intermediate 222, which underwent a Brook rearrangement followed by cyclopropane formation to yield anionic 223 in situ [192]. The

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

• peroxide functional group. As in the above-considered studies, the intramolecular cyclization of ozonolysis products can be performed with the use of the hydroperoxide group provided that there is an appropriate electrophilic center. The reaction of oxetanes 60a,b with ozone in methanol produced 3-alkoxy

Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C₂-symmetric building block: a strategy for the synthesis of decanolide natural products

• Bernd Schmidt and
• Oliver Kunz

Beilstein J. Org. Chem. 2013, 9, 2544–2555, doi:10.3762/bjoc.9.289

• carbene complex B [35] as precatalysts (Table 1). Phosphine-free precatalysts with a hemilabile alkoxy ligand are supposed to be well-suited for cross metathesis reactions [36][37]. With a moderate catalyst loading of 2.0 mol % of A, we isolated the expected cross metathesis product 11 in an acceptable

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• . This synthetic protocol is versatile and highly efficient with both primary and secondary azido derivatives as well as alkoxy and amido groups. The one-pot, two-step procedure afforded urea derivatives in high yield and purity via the isocyanate intermediate. To broaden the scope of the study, the