The total synthesis of D-chalcose and its C-3 epimer

• Jun Sun,
• Song Fan,
• Zhan Wang,
• Guoning Zhang,
• Kai Bao and
• Weige Zhang

Beilstein J. Org. Chem. 2013, 9, 2620–2624, doi:10.3762/bjoc.9.296

• deprotected and oxidized to yield the corresponding aldehyde. Our first step toward this goal was to select appropriate protective groups. Diol 6 was initially converted into benzylidene derivative 8 (α,α-dimethoxytoluene/PPTS/CH2Cl2); 8 was subjected to a regioselective reductive ring-opening reaction [23

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

• . This data is compatible with the observed regioselectivity [37]. Steric factors can also exert notable influence, but they would guide regioselectivity in the same direction. In a subsequent step, we decided to preliminarily study the ring opening reaction of the 3-trifluoromethyl-2-isoxazolines in

• allylbenzene (5a). Synthesis of 3-trifluoromethyl-2-isoxazolines and isoxazoles by reaction between aldoxime 2 and olefins or alkynes in the presence of DIB. FMO coefficients of the 1,3-dipole 4 and representative dipolarophiles (atomic orbital is indicated in parentheses). Ring opening reaction of 3

A protecting group-free synthesis of the Colorado potato beetle pheromone

• Zhongtao Wu,
• Manuel Jäger,
• Jeffrey Buter and
• Adriaan J. Minnaard

Beilstein J. Org. Chem. 2013, 9, 2374–2377, doi:10.3762/bjoc.9.273

• , an acid-catalyzed ring-opening reaction was carried out using HClO4 in THF/water at room temperature [22]. In the process of ring-opening, close to quantitative inversion of configuration at C-3 takes place [23][24], a result which was confirmed in our research as determination of the ee of both

• substrate and product shows a slight drop in ee from 88% to 86% (see Supporting Information File 1). Triol (2R,3S)-3 was obtained from (2R,3R)-4 in high yield by this regio- and stereoselective ring-opening reaction. Subsequently (2R,3S)-3 was converted into (S)-1 by treatment with 0.5 mol % of catalyst 2

• the literature [8][9]. Starting from nerol, Sharpless asymmetric epoxidation afforded the epoxide (2S,3R)-4 in a disappointing 74% ee, a result which is nevertheless in accordance with the reported values: 70–94% [25][26][27][28][29][30] (Scheme 4). Applying the same ring-opening reaction to epoxide

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

Beilstein J. Org. Chem. 2013, 9, 1677–1695, doi:10.3762/bjoc.9.192

• as a nucleophile under the same conditions, so the presence of the trimethylsilyl group is crucial to this ring-opening reaction. A proposed mechanism was based on NMR spectroscopic investigations as depicted in Figure 5. In the first step of the reaction, the active catalyst was formed by the

Thermochemistry and photochemistry of spiroketals derived from indan-2-one: Stepwise processes versus coarctate fragmentations

• Götz Bucher,
• Gernot Heitmann and
• Rainer Herges

Beilstein J. Org. Chem. 2013, 9, 1668–1676, doi:10.3762/bjoc.9.191

• facile decay mechanism for 1. The primarily formed benzyl-dialkoxymethyl biradical 4 should undergo a very facile ring-opening reaction to yield an ester biradical 7, which can either cleave into ethylene, carbon dioxide and o-xylylene (XY), or eliminate acetaldehyde (AA) to yield an acyl-benzyl

Exploration of an epoxidation–ring-opening strategy for the synthesis of lyconadin A and discovery of an unexpected Payne rearrangement

• Brad M. Loertscher,
• Yu Zhang and
• Steven L. Castle

Beilstein J. Org. Chem. 2013, 9, 1179–1184, doi:10.3762/bjoc.9.132

• epoxide 25. A Myers alkylation and a reagent-controlled Shi epoxidation were used to construct this compound in a highly stereoselective fashion. The bulky trityl group of 25 was intended to serve as a means of directing a ring-opening reaction to the distal carbon of the epoxide [19][20][21][22]. However

Preparation and ring-opening reactions of N-diphenylphosphinyl vinyl aziridines

• Ashley N. Jarvis,
• Andrew B. McLaren,
• Helen M. I. Osborn and
• Joseph Sweeney

Beilstein J. Org. Chem. 2013, 9, 852–859, doi:10.3762/bjoc.9.98

• -diphenylphosphinyl vinyl aziridines are prepared by a reaction of N-diphenylphosphinyl imines with α-bromoallyllithium in the presence of freshly fused ZnCl2. These aziridines undergo a ring-opening reaction with a variety of carbon and heteronucleophiles, in good yield, and generally with good regioselectivity

• , diethyl ether/light petroleum, 3:2, as an eluent). General procedures for the ring-opening reactions of N-diphenylphosphinyl vinyl aziridines Ring-opening reaction with lower-order cuprates: To dry CuI (5 equiv) in a flame-dried flask, under N2, was added diethyl ether (10 mL), and the suspension was

• /light petroleum (1:4); gradient elution to ethyl acetate). Ring-opening reaction with methyl magnesium Grignard: To magnesium (5 equiv) in diethyl ether (5 mL), under nitrogen, at 0 °C, was added MeI (5.4 equiv) in diethyl ether (1 mL) and the resulting mixture was stirred for 30 min, creating a grey

Ring-opening reaction of 2,5-dioctyldithieno[2,3-b:3',2'-d]thiophene in the presence of aryllithium reagents

• Hao Zhong,
• Jianwu Shi,
• Jianxun Kang,
• Shaomin Wang,
• Xinming Liu and
• Hua Wang

Beilstein J. Org. Chem. 2013, 9, 767–774, doi:10.3762/bjoc.9.87

• ring-opening reaction of 2,5-dioctyldithieno[2,3-b:3',2'-d]thiophene with aryllithium in THF at low temperature to generate 2'-arylthio-3,3'-bithiophene-2-carbaldehydes is studied. Nine examples are explored and all the products are characterized by 1H NMR, 13C NMR and HRMS. The relative relationship

• between the structures of aryl groups and the efficiency of ring-opening reactions are discussed. Keywords: aryllithium reagents; 2'-arylthio-3,3'-bithiophene-2-carbaldehyde; dithieno[2,3-b:3',2'-d]thiophene; nucleophilicity; ring-opening reaction; Introduction Due to the promising optical and

• . To construct DTT functional materials, deprotonation of DTT with organolithium reagents seems to be one of the most important approaches. However, the ring-opening reaction of DTT leading to the cleavage of the center ring can be observed in the presence of n-BuLi. In our previous work, we reported

One-pot tandem cyclization of enantiopure asymmetric cis-2,5-disubstituted pyrrolidines: Facile access to chiral 10-heteroazatriquinanes

• Ping-An Wang,
• Sheng-Yong Zhang and
• Henri B. Kagan

Beilstein J. Org. Chem. 2013, 9, 265–269, doi:10.3762/bjoc.9.32

• process, both N-debenzylation and a ring-opening reaction occurred. Diamino-alcohols 6a and 6b are enantiomers, and they can serve as precursors for the synthesis of hydroxy N-heterocyclic carbenes. Following the reported procedure for the preparation of N-heterocyclic carbenes [19][20], the enantiopure

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

• hexachloro derivative 94 was treated by Gilman and co-workers with excess dimethylsilyl chloride and magnesium in THF, the hexasilylated derivative 95 was produced and again a ring-opening reaction to a conjugated bisallene had taken place (Scheme 23) [70]. In closing this section on silicon-substituted

Photoreactions of cyclic sulfite esters: Evidence for diradical intermediates

• Rick C. White,
• Benny E. Arney Jr. and
• Heiko Ihmels

Beilstein J. Org. Chem. 2012, 8, 1208–1212, doi:10.3762/bjoc.8.134

• decarbonylation results in an alkyl radical. The latter reaction yields bibenzyl (4) and toluene (7) in the photoreaction of 8. It should be noted that the diradical BR2 may be formed also upon photoinduced ring-opening reaction of an intermediate oxirane 2a, which is not detectable in the reaction mixture

Alkoxide-induced ring opening of bicyclic 2-vinylcyclobutanones: A convenient synthesis of 2-vinyl-substituted 3-cycloalkene-1-carboxylic acid esters

• Xiufang Ji,
• Zhiming Li,
• Quanrui Wang and
• Andreas Goeke

Beilstein J. Org. Chem. 2012, 8, 650–657, doi:10.3762/bjoc.8.72

• , i.e., dibenzo-18-crown-6, did not show any improvement of the yield of compound 6a (Table 2, entry 8). In light of the above promising results, the substrate scope of this base-promoted ring-opening reaction was assessed by using a variety of cyclobutanones 4b–i (Scheme 3, Table 3). Diverse

Perhydroazulene-based liquid-crystalline materials with smectic phases

• Zakir Hussain,
• Henning Hopf and
• S. Holger Eichhorn

Beilstein J. Org. Chem. 2012, 8, 403–410, doi:10.3762/bjoc.8.44

• 1a and 1b were subsequently subjected to a ring-opening reaction to afford the cycloheptatrienes 4a and 4b. In a first step, the isomers 1 were first brominated in carbon tetrachloride [15], to produce the dibromides 2a and 2b. After the complete addition of bromine, triethylamine was added slowly

Synthesis of highly functionalized β-aminocyclopentanecarboxylate stereoisomers by reductive ring opening reaction of isoxazolines

• Melinda Nonn,
• Loránd Kiss,
• Reijo Sillanpää and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2012, 8, 100–106, doi:10.3762/bjoc.8.10

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

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

• migrations or hydride shifts. Simple Friedel–Crafts type reactions and cyclizations will not be covered. Review Ring opening reactions Several types of superelectrophiles are known to undergo ring opening reactions. The ring opening reaction step can be followed by the reaction with a nucleophile. For

Three step synthesis of single diastereoisomers of the vicinal trifluoro motif

• Vincent A. Brunet,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2009, 5, No. 61, doi:10.3762/bjoc.5.61

• there was no evidence for the involvement of an intermediate phenoxonium ion under these conditions. The ring opening reaction of 9b was explored under a variety of conditions and the best conversion and selectivity was obtained using chloroform at 100 °C in a sealed autoclave with a Teflon inner layer

Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with secondary amine nucleophiles

• Dingqiao Yang,
• Ping Hu,
• Yuhua Long,
• Yujuan Wu,
• Heping Zeng,
• Hui Wang and
• Xiongjun Zuo

Beilstein J. Org. Chem. 2009, 5, No. 53, doi:10.3762/bjoc.5.53

• and 5 mol % bisphosphine ligand (S)-p-Tol-BINAP. The trans-configuration of 3f was confirmed by X-ray crystallography. Keywords: chiral bisphosphine ligand; iridium catalyst; oxabicyclic alkenes; ring-opening reaction; Introduction Substituted dihydronaphthalenes are important molecules with

• (S)-p-Tol-BINAP were found to give better yields and reasonable enantioselectivities. Moreover, in the case of (S)-p-Tol-BINAP, the enantioselectivity is slightly higher than for (S)-BINAP (52% ee vs 35% ee); therefore, we decided to use (S)-p-Tol-BINAP as the ligand for this ring-opening reaction

• -catalyzed asymmetric ring-opening reaction of substrate 1c.a Supporting Information Experimental procedures and full characterization data for all the new compounds including optical rotations, IR, 1H NMR and 13C NMR, MS and elemental analysis are provided in the Supporting Information. In addition, X-ray

Synthesis of novel photochromic pyrans via palladium- mediated reactions

• Christoph Böttcher,
• Gehad Zeyat,
• Saleh A. Ahmed,
• Elisabeth Irran,
• Thorben Cordes,
• Cord Elsner,
• Wolfgang Zinth and
• Karola Rueck-Braun

Beilstein J. Org. Chem. 2009, 5, No. 25, doi:10.3762/bjoc.5.25

• detailed publication comparing substances with and without substituents in this position is in preparation. The results given in Figure 1a/b clearly demonstrate that the ring-opening reaction proceeds on a picosecond timescale. Since the stationary measurements do not reveal a change of absorption under

A short stereoselective synthesis of (+)-(6R,2′S)-cryptocaryalactone via ring- closing metathesis

• Palakodety Radha Krishna,
• Krishnarao Lopinti and
• K. L. N. Reddy

Beilstein J. Org. Chem. 2009, 5, No. 14, doi:10.3762/bjoc.5.14

• alcohol that was obtained from a regioselective ring-opening reaction of 2,3-epoxy alcohol 8. The known 2,3-epoxy alcohol 8 was synthesized from the corresponding dienyl alcohol by the well-established Sharpless asymmetric epoxidation conditions in >94% ee as described in literature [38][39]. Compound 8

• undergoes a reductive ring-opening reaction with Red-Al under standard reaction conditions to furnish the 1,3-diol 9 in 88% yield. Traces of 1,2-diol were oxidatively cleaved with NaIO4 in presence of catalytic amount of saturated NaHCO3 solution. Diol 9 was protected with anisaldehyde dimethylacetal in

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• Sharpless AD and AE reactions (Scheme 35). Elongation of the carbon skeleton of 256 was achieved by a ring-opening reaction using 257 to afford alkyne 258. Then Wittig reaction of the corresponding Wittig reagent prepared from 258 with aldehyde 259 followed by catalytic hydrogenation and deprotection

Hydrogenation of aromatic ketones, aldehydes, and epoxides with hydrogen and Pd(0)EnCat™ 30NP

• Steven V. Ley,
• Angus J. P. Stewart-Liddon,
• David Pears,
• Remedios H. Perni and
• Kevin Treacher

Beilstein J. Org. Chem. 2006, 2, No. 15, doi:10.1186/1860-5397-2-15

• ]. For these kind of substrates, catalysts based on Ni, Pd, and Pt have been used, and further efforts are directed toward improving the chemoselectivity and regioselectivity of this ring-opening reaction. [18][19] We now demonstrate that aryl aldehydes and ketones as well as aryl epoxides can also

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• afforded the corresponding azido-alcohols 11 and 12, isolated as single stereoisomers in excellent yield (95–98%). No other isomer of 11 or 12 was detected by NMR analysis, indicating that the ring-opening reaction is highly regioselective and results in the anti addition of the azido group on the opposite