Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• derivatives by HF/Py The ring opening reaction of aziridines 138a,b by treatment with hydrogen fluoride in pyridine afforded 3-fluorophenylalanine esters 139a,b. The subsequent enzymatic hydrolysis of esters 139a,b gave the threo-isomer 136 in an enantiomerically pure form [68][69] (Scheme 31). On the other

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• access various derivatives, such as 12 and 13, derived from the trapping and Baeyer–Villiger oxidation of 11, respectively, or compound 16, obtained via the ring opening reaction of 15 with an amine (Scheme 5). Taking the enolate intermediate derived from the addition of EtMgBr to coumarin as an example

• co-workers elaborated the copper-catalysed ring opening reaction of oxabicyclic alkene substrates using organolithium reagents, finding excellent anti selectivities and enantioselectivity (Scheme 12) [42]. During the optimisation studies, they discovered that when the Lewis acid BF3·OEt2 was employed

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• a certain extent Hg2+) initially induced a ring-opening reaction that was irreversibly followed by a fast ring closure–deprotonation–oxidation sequence to give styryl-substituted naphthoxazole derivatives as the products quantitatively. For the quinolizinium-substituted spirooxazine derivative, the

• ., 1aSO: λabs = 317 nm, 1aMC: λabs = 602 nm, in MeCN) [16]. In some instances, the ring-opening reaction may also be induced in the dark through the addition of particular metal cations that are able to coordinate to the phenolate oxygen atom and/or other additional coordinating atoms and substituents

• that have been introduced into the structure of the spirooxazine and spiropyran derivatives [17][18][19][20][21][22][23][24][25][26]. Regardless of whether the ring-opening reaction is induced by cations or irradiation, the coordination of metal ions to the substrate usually results in a negative

SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• 25 was suppressed under the same conditions (Table 2, entry 3). The SnCl4-catalyzed acetolysis of tribenzylated 25 offered the acetolysis product 26 in a low yield (27%) and occurred faster than with 6 and 21. The fast ring-opening reaction of 25 might have been attributed to the presence of three

• , SnCl4 and Sn(OTf)2 might have formed a coordination bond with the carbonyl oxygen atom of the C-5 NHAc group and the O-6 position of the glucose glucopyranosyl ring. In turn, this retarded the ring-opening reaction. The anchimeric participation of the NHAc group in stabilizing the axial conformation of

• . R = Me, Bn, PG = electron-donating protecting groups, electron-withdrawing protecting groups. Synthesis and acetolysis of 2,7-anhydro derivatives 21 and 25. Attempted acetolysis of 2,7-anhydro-NeuN3-based disaccharides 29, 33, and 37. Optimization of the ring-opening reaction of 6. Substantiation of

A photochemical determination of luminescence efficiency of upconverting nanoparticles

• Baptiste Amouroux,
• Clément Roux,
• Jean-Claude Micheau,
• Fabienne Gauffre and
• Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

• used to give a reasonable quantitative estimation of the upconversion phenomenon. In particular, we will exploit the ring-opening reaction since only the closed form 1-c presents a good spectral overlap with the visible emissions of the Er-UCNPs. In order to achieve a “user friendly” quantitative

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• hands, a selective epoxide ring-opening reaction with fatty acids 3 leading to the formation of the corresponding sn-1,3-protected monoacylglycerols (MAGs 4) was attempted (Scheme 3). Initially, commonly used solution-based protocols were tested in the ball mill [33]. For example, 2 was reacted with

• stearic acid (3a) in the presence of amines such as pyridine or tributylamine. However, the analysis of the reaction mixture only showed unreacted starting materials. In previous work, an acceleration of the oxirane ring-opening reaction with carboxylic acids [34] or alcohols [35] by using Lewis acid

• a promising one to mechanochemically access MAGs by ball milling. Experimentally, we attempted the cobalt-catalyzed epoxide ring-opening reaction by milling 2 with stearic acid (3a) in the presence of (S,S)-cat (2.5 mol %) and N,N-diisopropylethylamine (DIPEA; 1.0 equiv, Scheme 3a). Mechanistically

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• NMR analysis of the crude reaction mixture. Indeed, a slow ring-opening reaction took place upon standing in solution to mainly give the isoxazole isomer 28 along with much less of the target oxazole-bearing α-hydroximino ester 29. Extensive trials to alter the selectivity of the ring opening using

Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers

• Zsanett Benke,
• Melinda Nonn,
• Márton Kardos,
• Santos Fustero and
• Loránd Kiss

Beilstein J. Org. Chem. 2018, 14, 2698–2707, doi:10.3762/bjoc.14.247

• cyclooctene-fused isoxazoline (±)-16. ROM and transformations of lactam (±)-18. Isolated yields for compound (±)-5 formed in the ring-opening reaction of lactone (±)-3 with ethylene in ROM reactions with various catalysts. Isolated yields for compound (±)-6 formed in the ring-opening reaction of lactone (±)-4

• with ethylene in ROM reactions with various catalysts. Isolated yields for compound (±)-10 formed in the ring-opening reaction of lactone (±)-9 with ethylene in ROM reactions with various catalysts. Isolated yields for compounds formed in the ring-opening reaction of lactone (±)-14 and isoxazoline

• (±)-16 with ethylene in ROM reactions with various catalysts. Isolated yields for compound (±)-19 formed in the ring-opening reaction of lactam (±)-18 with ethylene in ROM reactions with various catalysts. Isolated yields for compound (±)-20 formed in the reaction of lactam (±)-19 in CM reactions with

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• , (c) reaction with DMAP, (d and e) desired reaction pathway (ester or amide bond formation), (d and f) reaction of the activated carboxyl group with water molecules. Mechanism of the epoxide ring opening reaction with the GO/RGO. Generation of the free amine (nucleophile) from the corresponding amine

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• the nucleophile at the 6-position of the substrate and subsequent ring-opening reaction [37][38]. Considering this impediment and the additional difficulties that may occur during purification of these cationic hetarenes the reaction and work-up conditions of Pd-mediated coupling reactions of benzo[b

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• ) with MS 4 Å. Asymmetric ring opening of meso-epoxides by p-xylenedithiol catalyzed by a (S,S)-(salen)Cr complex. Desymmetrization of meso-epoxide with thiophenol derivatives. Enantioselective ring-opening reaction of meso-epoxides with ArSH catalyzed by a C2-symmetric chiral bipyridyldiol–titanium

• complex. Enantioselective ring-opening reaction of stilbene oxides with ArSH catalyzed by a C2-symmetric chiral bipyridyldiol–titanium complex. Asymmetric desymmetrization of meso-epoxides using BINOL-based Brønsted acid catalysts. Lithium-BINOL-phosphate-catalyzed desymmetrization of meso-epoxides with

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• exhibited the best result. Aza-Diels–Alder and epoxide ring-opening reaction Manoury et al. have very recently reported facile synthesis of an enantiomerically pure inherently chiral calix[4]arene phosphonic acid (cR,pR)-121 from the readily available (cS)-enantiomer of calix[4]arene acetic acid 119 or its

• -opening reaction. Review Phase-transfer catalysis For the past three decades, asymmetric phase-transfer catalysis utilizing chiral quaternary ammonium salts has attracted great interest as a synthetic strategy since it provides quick access to a large number of enantiopure compounds employing only

• important transformations: phase-transfer catalysis, Henry reaction, Suzuki–Miyaura cross-coupling and Tsuji–Trost allylic substitution, hydrogenation, Michael addition, aldol and multicomponent Biginelli reactions, epoxidation, Meerwein–Ponndorf–Verley reduction, aza-Diels–Alder and epoxide ring-opening

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• and spectroscopic characterization of this elusive molecule obtained by electrocyclic ring-opening reaction of 230 through irradiation in a rigid medium at low temperature or by thermolysis at high temperature [153]. As shown in Scheme 37, compound 230 was synthesized through the addition of benzyne

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols

• Katrina Tait,
• Alysia Horvath,
• Nicolas Blanchard and
• William Tam

Beilstein J. Org. Chem. 2017, 13, 2888–2894, doi:10.3762/bjoc.13.281

• Becquerel, 67087 Strasbourg, France 10.3762/bjoc.13.281 Abstract The acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicylic alkene using alcohol nucleophiles were investigated. Although this acid-catalyzed ring-opening reaction did not cleave the cyclopropane unit as planned, this

• . Conclusion In conclusion, we have demonstrated the first examples of acid-catalyzed nucleophilic ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclic alkene with alcohols. Although this acid-catalyzed ring-opening reaction did not cleave the cyclopropane unit as planned, this represent the first

• -opening of cyclopropanated 3-aza-2-oxabicyclic alkene 19. Effects of acid catalysts on the ring-opening reaction of cyclopropanated 3-aza-2-oxabicyclic alkene 23a with alcohols. Effect of solvent on the ring-opening reactions of cyclopropanated 3-aza-2-oxabicyclic alkene 23a with alcohols. Scope of the

A new member of the fusaricidin family – structure elucidation and synthesis of fusaricidin E

• Marcel Reimann,
• Louis P. Sandjo,
• Luis Antelo,
• Eckhard Thines,
• Isabella Siepe and
• Till Opatz

Beilstein J. Org. Chem. 2017, 13, 1430–1438, doi:10.3762/bjoc.13.140

• separated by HPLC, the next steps were performed with the mixture. Performing the removal of the Cbz group with H2/Pd-C in THF, we encountered the formation of the N-(4-hydroxybutylated) product 25 resulting from a ring opening reaction of the solvent (Figure 4). This side reaction has been reported for

Palladium-catalyzed ring-opening reactions of cyclopropanated 7-oxabenzonorbornadiene with alcohols

• Katrina Tait,
• Oday Alrifai,
• Rebecca Boutin,
• Jamie Haner and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 2189–2196, doi:10.3762/bjoc.12.209

• cyclopropanated 8 and its proposed ring-opening mechanisms. Formation of the possible regioisomers for the ring opening of asymmetric C1-substituted cyclopropanated oxabenzonorbornadiene. Effects of palladium catalysts and catalyst equivalency on the ring-opening reaction of oxabicyclic alkene 8a with alcohols

The EIMS fragmentation mechanisms of the sesquiterpenes corvol ethers A and B, epi-cubebol and isodauc-8-en-11-ol

• Patrick Rabe and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1380–1394, doi:10.3762/bjoc.12.132

• (Scheme 2B). Furthermore, the high resolution GC–QTOF MS2 analysis of m/z = 179 reveals that the base peak ion is a direct precursor of m/z = 161 by the loss of water (Figure S1, Supporting Information File 1). Starting from cation A1+, a ring opening reaction with a proton transfer to the oxygen may

Regioselective palladium-catalyzed ring-opening reactions of C1-substituted oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylates

• Michael Edmunds,
• Mohammed Abdul Raheem,
• Rebecca Boutin,
• Katrina Tait and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 239–244, doi:10.3762/bjoc.12.25

• 1 undergoing a ring-opening reaction, which used p-iodotoluene and a palladium catalyst (Scheme 2) [14]. The result was the addition of the aryl group to the unsubstituted double bond followed by dehydration to give an unsymmetrical biphenyl derivative. However, there have not been any

• %, Table 2, entry 8); the same yield as was seen with p-iodoanisole, and the lowest yield was seen with o-iodonitrobenzene (47%, Table 2, entry 9). The effect of substitution on the bridgehead carbon of 1 was investigated to determine its impact on the outcome of the ring-opening reaction (Table 3). A wide

• for the ring-opening reaction of 2 with aryl iodides has been proposed based on the results obtained (Scheme 5). The reaction begins with the reduction of the palladium(II) catalyst, 4, to palladium(0) 5 by zinc. The Pd(0) catalyst complexes with the aryl iodide 6 forming the palladium-aryl complex 7

A concise and efficient synthesis of benzimidazo[1,2-c]quinazolines through CuI-catalyzed intramolecular N-arylations

• Xinlong Pang,
• Chao Chen,
• Ming Li and
• Chanjuan Xi

Beilstein J. Org. Chem. 2015, 11, 2365–2369, doi:10.3762/bjoc.11.258

• ), benzonitrile (1g) and di-(o-bromophenyl)iodonium salt 2 producing imine 3g and its subsequent cyclization in the presence of CuI. Acid-promoted ring-opening reaction from quinazoline 4c to 5. Optimization of reaction conditions for the synthesis of benzimidazo[1,2-c]quinazoline 4a from quinazolin-4(3H)-imine

Development of variously functionalized nitrile oxides

• Haruyasu Asahara,
• Keita Arikiyo and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2015, 11, 1241–1245, doi:10.3762/bjoc.11.138

• single experimental step [1][2]. In addition, cycloadducts serve as precursors of polyfunctionalized compounds by ring opening reaction followed by N–O bond fission [2][3]. Hence, functionalized nitrile oxides are clearly useful for the preparation of more complex systems. However, because the precursors

A carbohydrate approach for the formal total synthesis of (−)-aspergillide C

• Pabbaraja Srihari,
• Namballa Hari Krishna,
• Ydhyam Sridhar and
• Ahmed Kamal

Beilstein J. Org. Chem. 2014, 10, 3122–3126, doi:10.3762/bjoc.10.329

• on aspergillides, Achmatowicz adducts were utilized as the key source for the construction of the dihydropyran moiety and the side arm was synthesized using a Zipper rearrangement as a key reaction after an epoxide ring opening reaction of (R)-propylene oxide/(S)-propylene oxide with n-BuLi. In the

Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

• Francesco Trotta,
• Fabrizio Caldera,
• Roberta Cavalli,
• Andrea Mele,
• Carlo Punta,
• Lucio Melone,
• Franca Castiglione,
• Barbara Rossi,
• Monica Ferro,
• Vincenza Crupi,
• Domenico Majolino,
• Valentina Venuti and
• Dominique Scalarone

Beilstein J. Org. Chem. 2014, 10, 2586–2593, doi:10.3762/bjoc.10.271

• ring opening reaction of the cyclic dianhydride and the formation of ester bridges. Moreover, the relative intensity of the O–H stretching band (centered at 3435 cm−1) with respect to the intensity of the carbonyl stretching band is higher in the branched polymer than in the cross-linked nanosponge

Regio- and stereoselective synthesis of new diaminocyclopentanols

• Evgeni A. Larin,
• Valeri S. Kochubei and
• Yuri M. Atroshchenko

Beilstein J. Org. Chem. 2014, 10, 2513–2520, doi:10.3762/bjoc.10.262

• -purin-6-amine (7d) were used as nucleophiles (Figure 1). Starting amines were selected based on the fact that these motifs are common structural features in drug molecules. Optimization of the epoxide ring opening reaction of 3a The opening of epoxides with nucleophiles in the presence of Lewis acid or

• attack at the C1-oxirane carbon atom [29]. Synthesis of diaminocyclopentanols using epoxide 3b Next, we explored the influence of the N,N-dibenzylamino group on the ring opening reaction using the optimized reaction conditions for 3b (Table 2). Surprisingly, the ring opening of N,N-dibenzyl derivative 4b

• presence of C(2)H-C(5)H and C(1)H-NCH3 NOEs were supportive of the assigned configuration of 13a (Supporting Information File 2). The ring opening reaction of epoxide 6b with 9H-purin-6-amine (7d) in the presence of Cs2CO3 (Table 4, entry 2) showed the higher level of regioselectivity in comparison with

One-pot stereoselective synthesis of α,β-differentiated diamino esters via the sequence of aminochlorination, aziridination and intermolecular S_N2 reaction

• Yiwen Xiong,
• Ping Qian,
• Chenhui Cao,
• Haibo Mei,
• Jianlin Han,
• Guigen Li and
• Yi Pan

Beilstein J. Org. Chem. 2014, 10, 1802–1807, doi:10.3762/bjoc.10.189

• directly from α,β-unsaturated esters has been developed. The reaction sequence includes copper-catalyzed aminochlorination, aziridination and SN2 nucleophilic ring-opening reaction. This one-pot reaction is operationally convenient and can tolerate a variety of substrates affording the target products in

Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin

• Melanie Rauschenberg,
• Eva-Corrina Fritz,
• Christian Schulz,
• Tobias Kaufmann and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2014, 10, 1354–1364, doi:10.3762/bjoc.10.138

• HisHis towards immobilized NANA in comparison with the glycosides of glucose (Glc), galactose (Gal) and mannose (Man) (Figure 1). In this study, we exploit the epoxide ring opening reaction of amine-tethered carbohydrates on epoxide-terminated SAMs [42] to print carbohydrate microarrays on silicon and

• epoxide ring opening reaction with amines is much faster at elevated temperatures, the surface of oxidized, patterned PDMS stamps was coated with 2-[methoxy(polyethyleneoxy)propyl]trimethylsilane (PEG silane) [51]. The PEG coated stamps provided optimal wetting of the stamp by the carbohydrate ink