Unprecedented deoxygenation at C-7 of the ansamitocin core during mutasynthetic biotransformations

• Tobias Knobloch,
• Gerald Dräger,
• Wera Collisi,
• Florenz Sasse and
• Andreas Kirschning

Beilstein J. Org. Chem. 2012, 8, 861–869, doi:10.3762/bjoc.8.96

• produces the expected ansamitocin derivative 14 in good yield (Scheme 4) [28]. Besides the ester side chain, compound 14 also lacks the epoxy functionality and the N-methyl group. These two tailoring steps finalize the biosynthesis of ansamitocin P-3 (AP-3, 4) and occur only after acylation has taken place

An easy α-glycosylation methodology for the synthesis and stereochemistry of mycoplasma α-glycolipid antigens

• Yoshihiro Nishida,
• Yuko Shingu,
• Yuan Mengfei,
• Kazuo Fukuda,
• Hirofumi Dohi,
• Sachie Matsuda and
• Kazuhiro Matsuda

Beilstein J. Org. Chem. 2012, 8, 629–639, doi:10.3762/bjoc.8.70

• -glycosyl bromide species [32]. In the pathway using DMF, the α-glycosylation is routed via α-glycosyl cationic imidate 3, which was predicted in former studies [33] and evidenced in our preceding NMR and MS study [25][26]. The reaction between 1 and (S)-glycidol in CH2Cl2 (+ TMU) gave a mixture of epoxy

Intramolecular carbenoid ylide forming reactions of 2-diazo-3-keto-4-phthalimidocarboxylic esters derived from methionine and cysteine

• Marc Enßle,
• Stefan Buck,
• Roland Werz and
• Gerhard Maas

Beilstein J. Org. Chem. 2012, 8, 433–440, doi:10.3762/bjoc.8.49

• . Characteristics are the signals for the NCH proton (13a: δ = 4.60 ppm; 13b: δ = 4.67 ppm) and the two bridgehead carbons of the epoxy bridge (13a: δ = 86.60 and 94.13 ppm; 13b: δ = 86.75 and 94.04 ppm). While a CI mass spectrum of 13b showed a weak molecular-ion peak for the dimer (the base peak representing the

• monomer unit), in the case of 13a, even under these mild conditions of chemical ionisation, the spectrum showed no peak at m/z greater than that for the monomer, which was again the base peak. The relative stereochemistry shown in Scheme 4, with the two epoxy bridges in syn relationship and the

Improved syntheses of high hole mobility phthalocyanines: A case of steric assistance in the cyclo-oligomerisation of phthalonitriles

• Daniel J. Tate,
• Rémi Anémian,
• Richard J. Bushby,
• Suwat Nanan,
• Stuart L. Warriner and
• and Benjamin J. Whitaker

Beilstein J. Org. Chem. 2012, 8, 120–128, doi:10.3762/bjoc.8.14

• calibrated with indium (mp 156.60, ΔH = 28.53 J·g−1) and a heating/cooling rate of 10 °C·min−1. Time-of-flight photoconductivity studies The cells were assembled in a laminar-flow hood to avoid contamination by dust or grease. Each ITO-coated glass slide was connected to a copper wire by epoxy resin (Aradite

• ) and the tip of the wire was bonded to the ITO surface with silver paint (RS 186-3600). The two halves were separated by a PET spacer (Goodfellow Cambridge Limited) with a thickness of 23 μm, held in position with clips and secured with epoxy resin. The thickness of the cell (d) was accurately

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• and co-workers reported the synthesis of epoxy-based nonlinear optical polymers 144 functionalized by post-azo coupling (Figure 23; [130]). The parent polymer backbone was synthesized from diglycidyl ether of bisphenol A and aniline and was further functionalized by diazotized amine 83 (Figure 15

• -functionalized chromophores incorporated into a polymer backbone Rpol [18][50][51][52][53][122][123][124]. Structure of polyphosphazene polymers bearing NLO-phores [125][126][127] and some other recent examples of nonlinear optical polymers [19][128]. Epoxy- and silica-based polymers functionalized with 4,5

A practical microreactor for electrochemistry in flow

• Kevin Watts,
• William Gattrell and
• Thomas Wirth

Beilstein J. Org. Chem. 2011, 7, 1108–1114, doi:10.3762/bjoc.7.127

• without any added electrolyte [4][5]. Atobe et al. constructed a thin layer flow cell from platinum and/or glassy carbon plates (3 × 3 cm), separated by adhesive tape (80 µm), with a space left in between to act as the channel, and the devices were sealed with epoxy resin [6]. They reported the self

Functionalization of anthracene: A selective route to brominated 1,4-anthraquinones

• Kiymet Berkil Akar,
• Osman Cakmak,
• Orhan Büyükgüngör and
• Ertan Sahin

Beilstein J. Org. Chem. 2011, 7, 1036–1045, doi:10.3762/bjoc.7.118

• structure of tetralin oxide 26 produced from the corresponding halohydrine 25, shows the existence of hydrogen bonding between the hydroxy and the epoxy group, which has the same stereochemistry as that of compound 5 [1][14][15]. Thus, the fact that compound 23 was not obtained from 17 can be attributed to

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• . Acyloxylated alkynyl oxiranes 28 and 30 have also proved to be versatile building blocks for the synthesis of divinyl ketones 29 [29], 2,5-disubstituted furans 31 [30] and difurylmethane derivatives 32 [31], respectively (Scheme 10). Epoxy alkynes can also be transformed with high stereoselectivity into ketals

Metathesis access to monocyclic iminocyclitol-based therapeutic agents

• Ileana Dragutan,
• Valerian Dragutan,
• Carmen Mitan,
• Hermanus C.M. Vosloo,
• Lionel Delaude and
• Albert Demonceau

Beilstein J. Org. Chem. 2011, 7, 699–716, doi:10.3762/bjoc.7.81

• tetrahydropyridine scaffold 72 allowed an efficient synthesis of 1-deoxynojirimycin 62, and its stereoisomers 65 and 66. Thus, acid hydrolysis of the epoxy ring in the anti isomer 73 (H2SO4/dioxane/H2O, 0.2:3:2) gave 1-deoxynojirimycin (62) and 1-deoxyaltronojirimycin (65) in a 1:1 ratio and in 89% yield. Conversely

• modified Upjohn conditions, Scheme 22). For iminocyclitols containing trans diols at the 3- and 4-positions an epoxy functionality at the double bond in 125 was introduced. While the syn epoxide 128 led to a mixture of fagomine (129) and 3,4-di-epi-fagomine (130), the anti epoxide 127 gave 129 selectively

Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations

• Jakub Saadi,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, 1229–1245, doi:10.3762/bjoc.6.141

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

• probably yield polymer particles with a bimodal size distribution. The first polyadditions in miniemulsion carried out were the reactions of polyepoxides and hydrophobic diamines, bisphenols, and dimercaptans [11]. Stable latexes of epoxy resins could be obtained and apparent molecular weights up to 20,000

• variety of polymers, e.g., with epoxy, polyurethane (Figure 7), and polyurea, or based on synthetic polyamines, polythiourea, crosslinked starch, dextran or polyethylene imine [116]. Therefore, the functionality can be directly implemented in the capsules by using an excess of one of the monomers, or by

Synthesis, characterization and photoinduced curing of polysulfones with (meth)acrylate functionalities

• Cemil Dizman,
• Sahin Ates,
• Lokman Torun and
• Yusuf Yagci

Beilstein J. Org. Chem. 2010, 6, No. 56, doi:10.3762/bjoc.6.56

• after polymerization. The second involves direct copolymerization of functionalized monomers [4][5][6]. An increasing topic of interest concerns cooperation of PSUs with epoxy resins via end group functionalization or blending. Engineering thermoplastics based on PSU have been widely used to overcome

• the problems associated with the brittleness of epoxy resins [7][8][9][10][11]. Telechelic oligomers are defined as the prepolymers carrying one or more functional end groups. They take part in further polymerization or other reactions through their functional end groups [12]. The functionality of the

Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

• Gajanan M. Pawar,
• Jochen Weckesser,
• Siegfried Blechert and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, No. 28, doi:10.3762/bjoc.6.28

• -3,6-Epoxy-1,2,3,6-tetrahydrophtalic anhydride (10.0 g, 60.0 mmol), 2-dimethylaminoethanol (6.3 mL, 62.0 mmol, 1.03 equiv) and p-toluenesulfonic acid (590 mg, 3.1 mmol, 5 mol%) were dissolved in 120 mL of THF and stirred at room temperature for 8 h. The white precipitate was filtered, washed with

Diastereoselective functionalisation of benzo-annulated bicyclic sultams: Application for the synthesis of cis-2,4-diarylpyrrolidines

• Susan Kelleher,
• Pierre-Yves Quesne and
• Paul Evans

Beilstein J. Org. Chem. 2009, 5, No. 69, doi:10.3762/bjoc.5.69

• dependent on the electronic nature of the aryl motif and of the reaction solvent. Experimental Representative experimental procedures are shown for compounds 7a, 13a, 18b, 24a, 27, 31, 35, 39. For full experimental details see accompanying Supporting Information. (±)-(1S,10R,11R)-Epoxy-8-thia-9-azatricyclo

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

• described. The route starts from either syn- or anti-α,β-epoxy alcohols and takes a direct approach in that each of the three steps introduces a fluorine atom in a regio- and stereo-specific manner. Starting from either the syn- or the anti-α,β-epoxy alcohol, stereospecific reactions generate two separate

• practical route to this class of compounds is required if these vicinal trifluoro motifs are to be applied usefully. A three step strategy, as illustrated in Scheme 2, starting from diastereoisomeric syn- or anti-α,β-epoxy alcohols A was envisaged, each step incorporating a fluorine atom in a stereospecific

• reactions following Sharpless’ methodology [16]. The anti-epoxy alcohols were easily generated, however it proved more difficult to prepare the syn-epoxides cleanly. Treatment with titanium isopropoxide (Ti(OiPr)4) and D-diisopropyl tartrate (D-DIPT) favoured formation of the anti-α,β-epoxy alcohols. In the

The development and evaluation of a continuous flow process for the lipase- mediated oxidation of alkenes

• Charlotte Wiles,
• Marcus J. Hammond and
• Paul Watts

Beilstein J. Org. Chem. 2009, 5, No. 27, doi:10.3762/bjoc.5.27

• ), 97 (77), 85 (15), 95 (100), 83 (15), 69 (15) and 55 (25); GC-MS tR = 5.26 min. The spectroscopic data obtained for 1-methylcyclohexene oxide (7) was consistent with that reported within the literature [36]. 1,2-Epoxy-1-phenylethane (styrene oxide) A pre-mixed solution containing styrene (9, 0.1 M

• -epoxy-1-phenylethane as a colourless oil (0.086 g, 99.2% yield); 1H NMR (400 MHz, CDCl3) δ 2.75 (dd, J = 2.8, 5.6, 1H), 3.08 (dd, J = 4.1, 5.6, 1H), 3.80 (dd, J = 2.8, 4.1, 1H) and 7.24–7.33 (m, 5H); 13C NMR (100 MHz, CDCl3) δ 51.0 (CH2), 51.1 (CH), 125.3 (2 × CH), 128.0 (CH), 128.2 (2 × CH) and 137.5

• (C); m/z (EI) 121 (M++1, 5%), 120 (20), 119 (50), 92 (25), 91 (100), 89 (40) and 77 (20); GC-MS tR = 5.37 min. The spectroscopic data obtained for 1,2-epoxy-1-phenylethane was consistent with that reported within the literature [37]. cis-1,2-Diphenyloxirane (cis-stilbene oxide, 13) A solution

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

• wherein a chiral 2,3-epoxy alcohol was the starting material and Sharpless asymmetric epoxidation and Carreira asymmetric alkynylation were used as key steps for generating unambiguous assigned stereocenters. More importantly, the Grubbs’ ring-closing metathesis protocol was applied to construct the final

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

• absolute configuration of natural-8 at C-8 to R (Scheme 3). In their synthesis, asymmetric epoxidation of 19 directed by L-(+)-diisopropyl tartrate gave epoxy alcohol 20; the THF ring of 21 was then constructed under CSA catalyzed one-pot transformation. After deprotection of the isopropylidene acetal of

• ,19S,20S)-cis-murisolin (112), and (15R,16R,19R,20S)-murisolin A (121) (Scheme 18). The mono-THF moieties were synthesized from epoxy alcohol 122 by using Sharpless AD-mix-β for the threo-trans-threo THF moiety 123, a AD-mix-β followed by the Mitsunobu reaction for the erythro-cis-threo THF moiety 125

Diels- Alder reactions using 4,7-dioxygenated indanones as dienophiles for regioselective construction of oxygenated 2,3-dihydrobenz[f]indenone skeleton

• Natsuno Etomi,
• Takuya Kumamoto,
• Waka Nakanishi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2008, 4, No. 15, doi:10.3762/bjoc.4.15

• and [4.4.3]propellane. The addition of Lewis acid did not affect the product ratio, whereas the use of the 6-bromoindanetrione exclusively afforded the latter propellane. On the other hand, DAR of benzyne derived from bromoindan and furan gave 5,8-epoxy-2,3-dihydrobenz[f]indene, which was subjected to

• B; quinone route) [28]; 2) regioselective ring-opening of 5,8-epoxy-2,3-dihydrobenz[f]indenone 11 derived from benzyne 10 and furan (9) (path C, benzyne route). Now we report that both of the methods are effective for the construction of the 2,3-dihydrobenz[f]indenone skeleton, but not for the

• examined by treatment of bromoindanone acetal 25, prepared from bromoindanone 18, with a base in the presence of furan (9) (Scheme 3). Application of Giles' protocol [41] using sodium amide as a base in the presence of a large excess amount (ca. 15 equivalents) of furan (9) in THF gave 5,8-epoxy-2,3