Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence

• Attila Márió Remete,
• Melinda Nonn,
• Santos Fustero,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2017, 13, 2364–2371, doi:10.3762/bjoc.13.233

• , namely oxazoline derivative (±)-21 (Scheme 10). This is in high contrast to the transformation of (±)-14 (Scheme 7). Interestingly, when (±)-20 is treated with Deoxofluor in excess, again, differently from its all-cis counterpart (±)-14, two fluorinated oxazolines in nearly 1:1 ratio are obtained: (±)-22

Iodoarene-catalyzed cyclizations of N-propargylamides and β-amidoketones: synthesis of 2-oxazolines

• Somaia Kamouka and
• Wesley J. Moran

Beilstein J. Org. Chem. 2017, 13, 1823–1827, doi:10.3762/bjoc.13.177

• Somaia Kamouka Wesley J. Moran Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK. Tel: +44-1484-473741 10.3762/bjoc.13.177 Abstract Two complementary iodoarene-catalyzed methods for the preparation of 2-oxazolines are presented. The first involves the

• -oxazolines, which are valuable heterocycles found in ligand scaffolds, natural products such as the leupyrrins [18][19], and potential pharmaceuticals (Figure 1) [20][21][22]. Traditional routes to this heterocycle include the dehydration of amino alcohols with carboxylic acids, however, this process

• ][26][27][28][29]. Saito and co-workers have reported the cyclization of propargylamides to form oxazoles rather than oxazolines under stoichiometric and, more recently, catalytic hypervalent iodine conditions [30][31]. Various other methods for the cyclization of unsaturated amides have been reported

Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

• Jimena E. Díaz,
• Silvia Ranieri,
• Nadia Gruber and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145

• reported the MW-assisted synthesis of 1,4,5,6-tetrahydropyrimidines and their homologues by cyclodehydration reactions promoted by polyphosphoric acid (PPA) esters PPE and PPSE [58][59][60]. This strategy was successfully applied to the synthesis of 1-aryl-2-imino-1-azacycloalkanes [61], 2-oxazolines, 5,6

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• adopted one is 2-chloro-1,3-dimethylimidazolinium chloride (DMC). In the presence of an excess of DMC and an amine base (typically NEt3) mono-, di-, and oligosaccharides are all selectively activated at the anomeric position. Some highlighted examples are described below. 4.1.1 Accessing oxazolines and

• interesting to note that these oxazolines can then be transglycosylated in one pot using a mutant endo-N-acetylglucosaminidase [69] (and as reviewed in Noguchi et al. [70]). This demonstrates the tremendous potential of these intermediates not only in classic organic synthesis but also in chemoenzymatic

• anomeric center by the C2–OH that is then opened by the primary OH at C6 to form the stable product (pathway B). The Shoda group has demonstrated the powerfulness of this one pot access to sugar oxazolines: these oxazolines can be used in transglycosylation reactions using mutant endoglycosidases (Scheme

Cyclodextrins tethered with oligolactides – green synthesis and structural assessment

• Cristian Peptu,
• Mihaela Balan-Porcarasu,
• Alena Šišková,
• Ľudovít Škultéty and
• Jaroslav Mosnáček

Beilstein J. Org. Chem. 2017, 13, 779–792, doi:10.3762/bjoc.13.77

• ) of cyclic esters [6], oxiranes [7] and oxazolines [8]. However, the ROP of cyclic esters should also be considered as a method of producing polymer-modified CDs with some particular features, such as possibility of employing green polymerization procedures and availability of renewable monomers like

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• , only para isomers 279 were formed in moderate 33% and 49% yields, respectively. On the contrary, when oxazolines 280 or 281 were used as ligands, mainly meta isomers 278 were formed with high yields. Cheng et al. have obtained 1-indanone 285 from octa-1,7-diyne (282) and cyclopentenone 239 as a result

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides

• Ilya V. Efimov,
• Marsel Z. Shafikov,
• Nikolai A. Beliaev,
• Natalia N. Volkova,
• Tetyana V. Beryozkina,
• Wim Dehaen,
• Zhijin Fan,
• Viktoria V. Grishko,
• Gert Lubec,
• Pavel A. Slepukhin and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233

• substitution of the β-H atom of the enamines 1a,b after treatment with hydroxamoyl chlorides 2a,d,g. The intermediate A undergoes cyclization to oxazolines 3a–c via addition of its hydroxy group onto the double bond of the enamine fragment. This kind of cyclization was ruled out by Elliott et al. [36] because

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• heterocyclisation to form thiazolines or oxazolines, and radical-mediated reactions between unactivated carbons. Future prospects for RiPP pathway discovery and characterisation will also be highlighted. Keywords: biosynthesis; cyclisation; enzymes; peptides; RiPPs; Introduction Nature employs a number of routes

• the RiPP, as they fundamentally change the shape of a molecule, which can be critical for receptor binding or for protection from proteolysis. Examples include amide bonds, heterocyclisation to form thiazolines or oxazolines [24] (Figure 2), oxidative carbon–carbon bond formation [25] and thioether

• peptides for each of these molecules. The sequence highlighted in blue in PatE corresponds to the core peptide for patellamide C, another macrocyclic RiPP that contains thiazoles and oxazolines. Formation of thiazoles and oxazoles in RiPPs. A) Biosynthesis of microcin B17. B) Mechanistic models for the

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

• . Consequently, a variety of other ligand classes derived from oxazolines or other nitrogen heterocycles were explored and eventually, several highly effective ligand systems were found that have considerably enhanced the range of functionalized and unfunctionalized olefins that can be hydrogenated with high

• but without irradiation. In initial model studies using neopentyl chloride and a commercially available solution of KPPh2 in THF we obtained high yields of neopentyldiphenylphosphine under reflux conditions [19]. Encouraged by these results, a series of chloroalkyl-substituted oxazolines 2 were

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• copper carbenoids to α-nitrogen C(sp3)–H bonds of amides (Scheme 11) [46]. A wide range of bis(oxazolines) were evaluated as chiral ligands in dry dichloromethane with NaBARF as additive. Three catalytic systems, based on ligands (−)-45a, (+)-45a and (4S)-1e, showed a better performance (>82% ee). The

Spiro-fused carbohydrate oxazoline ligands: Synthesis and application as enantio-discrimination agents in asymmetric allylic alkylation

• Jochen Kraft,
• Martin Golkowski and
• Thomas Ziegler

Beilstein J. Org. Chem. 2016, 12, 166–171, doi:10.3762/bjoc.12.18

• ; carbohydrates; oxazolines; palladium; spiro compounds; Introduction The design of new chiral ligands for stereo-differentiating metal catalysts that enable asymmetric syntheses is still a highly active field of research in organic chemistry, for there is a continuously growing demand for enantiomeric pure

• substitution using similar PyOx ligands are currently under investigation and will be published elsewhere. Pd-catalyzed cleavage of spiro-bis(isooxazoline) ligand A to isoxazole B and Pd-complex D prepared from spiro-oxazoline C. Synthesis of 2-benzylsulfanyl-1,3-oxazolines 7 and 8. Pd-catalyzed cross coupling

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

• situ along with chiral oxazolines [16][17], N-oxides [19] or amines [18][20][21] as ligands or organocatalysts. In these nitrosoaldol contexts, the chiral agents induce asymmetry by virtue of their influence over the enolate reaction partner. Achieving asymmetric induction in the nitroso–ene reaction

Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

• Madhuri Vangala and
• Ganesh P. Shinde

Beilstein J. Org. Chem. 2015, 11, 2289–2296, doi:10.3762/bjoc.11.249

• spirooxazolines are stable and were obtained in good yield with high stereoselectivity due to the conformational rigidity imparted by the 3,4-isopropylidene group. Keywords: fructose; oxazoline; riboside; Ritter reaction; spiro; Introduction 2-Oxazolines represent a unique class of 5-membered heterocyclic

• ) [4][5][6]. The strong affinity of the nitrogen in oxazoline towards metal makes the chiral derivatives excellent catalysts for asymmetrical transformations [7][8][9][10]. The amphiphilicity and biocompatibility of poly-2-substituted-2-oxazolines gained them recognition as biomaterials for polymer

• therapeutics [11][12][13]. Traditionally, oxazolines are used as protecting groups in organic synthesis [14]. Several efficient methods for the construction of the 2-oxazoline functionality are reported in the literature from alkenes, carboxylic acid derivatives, nitriles [15][16][17][18][19], etc. In

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• %). The oxazolines were prepared from enantiomerically pure α-aminoalcohols. The structures of the synthesized palladium complexes were confirmed by NMR, FTIR, TOFMS, UV–visible spectroscopic analysis and X–ray diffraction. The optical properties of the complexes were evaluated by the determination of the

• determined. Keywords: aminoalcohols; catalysis; dye decolorization; optical properties; oxazolines; palladium complexes; Introduction Palladium complexes have been used as starting materials to prepare polymers [1], agrochemicals [2], pharmaceuticals [3], flavors and fragrances [4]. They have also been

• structural features have been used in diverse reactions [8]. The importance of these ligands lies in the fact that the stereogenic centers are kept in close proximity to the metal and thereby having a strong and direct influence on the stereochemical course of the metal-catalyzed process. Oxazolines possess

Photochemical approach to functionalized benzobicyclo[3.2.1]octene structures via fused oxazoline derivatives from 4- and 5-(o-vinylstyryl)oxazoles

• Ivana Šagud,
• Simona Božić,
• Željko Marinić and
• Marija Šindler-Kulyk

Beilstein J. Org. Chem. 2014, 10, 2222–2229, doi:10.3762/bjoc.10.230

• : (b)). From the NOESY spectrum was evident that the HA is oriented towards the methano bridge. The diastereomeric fused tetracyclic oxazolines rel-(2S)-8a and rel-(2R)-8b (Scheme 2, Figure 1), that were obtained on irradiation of cis/trans-4-(2-vinylstyryl)oxazole (1), are more stable than 10 but not

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

• Andrea Temperini,
• Massimo Curini,
• Ornelio Rosati and
• Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

• intramolecular nucleophilic substitution reactions e.g. epoxides from β-hydroxy phenyl selenides [9][10], N-benzoyl- and N-tosyl-1,3-oxazolidin-2-ones from β-hydroxyalkyl phenyl selenides [11], N-arenesulfonylazetidines from γ-(phenylseleno)alkyl arylsulfonamides [12], N-acylaziridines [13], 1,3-oxazolines

Synthesis of 1-[bis(trifluoromethyl)phosphine]-1’-oxazolinylferrocene ligands and their application in regio- and enantioselective Pd-catalyzed allylic alkylation of monosubstituted allyl substrates

• Zeng-Wei Lai,
• Rong-Fei Yang,
• Ke-Yin Ye,
• Hongbin Sun and
• Shu-Li You

Beilstein J. Org. Chem. 2014, 10, 1261–1266, doi:10.3762/bjoc.10.126

• needed to confirm this hypothesis. Conclusion In summary, we have synthesized a class of novel and efficient bis(trifluoromethyl)phosphine-oxazolines as π-acceptor ligands which have shown good to excellent regio- and enantioselectivity for the Pd-catalyzed asymmetric allylic alkylation reaction of

A one-pot synthesis of 3-trifluoromethyl-2-isoxazolines from trifluoromethyl aldoxime

• Raoni S. B. Gonçalves,
• Michael Dos Santos,
• Guillaume Bernadat,
• Danièle Bonnet-Delpon and
• Benoit Crousse

Beilstein J. Org. Chem. 2013, 9, 2387–2394, doi:10.3762/bjoc.9.275

• . When the oxidation is carried out with DIB, weak acetic acid instead of strong trifluoroacetic acid is liberated, and the decomposition of the oxazolines is avoided. Faced with the moderate yield of 1a, we followed the reaction by using 19F NMR. The measurement of the crude mixture with 19F NMR

Enantioselective reduction of ketoimines promoted by easily available (S)-proline derivatives

• Martina Bonsignore,
• Maurizio Benaglia,
• Laura Raimondi,
• Manuel Orlandi and
• Giuseppe Celentano

Beilstein J. Org. Chem. 2013, 9, 633–640, doi:10.3762/bjoc.9.71

• -established methodology to perform enantioselective reductions of carbon nitrogen double bonds [1]. In the past decade different classes of enantiomerically pure Lewis bases have been developed, including N-formyl derivatives, oxazolines, imidazole derivatives, sulfonamides and picolinamides [2][3]. Some of

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

• as such [46]. trans-Imidazolidine 12b could also be used as a precursor of the corresponding Nα,Nβ-deprotected α,β-diaminocarboxylamide, by hydrolysis under acidic conditions, in analogy with deprotection reactions of imidazolidines, imidazolines and oxazolines in the literature [16][47][48]. However

Rh(III)-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

• Satoshi Takebayashi,
• Tsubasa Shizuno,
• Takashi Otani and
• Takanori Shibata

Beilstein J. Org. Chem. 2012, 8, 1844–1848, doi:10.3762/bjoc.8.212

• ]. Planar chiral 1,2-disubstituted ferrocene derivatives are usually synthesized by using diastereoselective ortho-lithiation of monosubstituted ferrocenes with an appropriate chiral ortho-directing substituent such as chiral amines, sulfoxides, and oxazolines [3]. However, this method suffers from low atom

Facile synthesis of nitrophenyl 2-acetamido-2-deoxy-α-D-mannopyranosides from ManNAc-oxazoline

• Karel Křenek,
• Petr Šimon,
• Lenka Weignerová,
• Barbora Fliedrová,
• Marek Kuzma and
• Vladimír Křen

Beilstein J. Org. Chem. 2012, 8, 428–432, doi:10.3762/bjoc.8.48

• % yield) or from methyl 4,6-O-benzylidene-α-D-glucopyranoside (5 steps, 23%). Unfortunately, in our hands this synthetic procedure did not afford the published yields, namely in the triflate and consequent azide substitution steps. Oxazolines, such as 3, have been used as glycosylation agents in the

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

• example, 2-oxazolines were shown [14] to form products with arenes and a mechanism was proposed involving ring opening of the superelectrophile (13, Scheme 2). The ring opening step effectively separates the positive charge centers, as the superelectrophile isomerizes from a 1,3-dication 13 to a 1,5

• . Thus, superelectrophiles tend to rearrange by reaction steps similar to monocationic rearrangements. Superelectrophilic activation of the acetyl cation. Ring opening of diprotonated 2-oxazolines. AlCl3-promoted ring opening of isoxaolidine 16. Ring-opening reactions of cyclopropyl derivatives

Synthesis and crystal structures of multifunctional tosylates as basis for star-shaped poly(2-ethyl-2-oxazoline)s

• Richard Hoogenboom,
• Martin W. M. Fijten,
• Guido Kickelbick and
• Ulrich S. Schubert

Beilstein J. Org. Chem. 2010, 6, 773–783, doi:10.3762/bjoc.6.96

• -oxazolines resulting in star-shaped polymers. The synthesis of the tosylates was performed by esterification of the corresponding alcohols with tosyl chloride. Recrystallization of these tosylate compounds afforded single crystals, and the X-ray crystal structures of di-, tetra- and hexa-tosylates are

• polymer from the acetylene-precursor polymer. To overcome the limitations of multi-halide, multi-triflate initiators and post-modification methods, we investigated the use of multi-tosylate initiators for the CROP of 2-oxazolines as depicted in Figure 1. The advantages of multi-tosylate initiators are

• multi-tosylates as initiators for the CROP of 2-oxazolines since they lead to side reactions with the cationic oxazolinium propagating species. Multi-tosylate crystal structures Recrystallization of the prepared multi-tosylates from ethanol or ethanol–acetone mixtures directly gave single crystals

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