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

• the secondary alcohol at C-2. The synthesis by Faraldos runs via epoxidation of fluoronerol, subsequent acetylation of the alcohol and solvolysis. In 2010, Waymouth reported the chemoselective, catalytic oxidation of glycerol to dihydroxyacetone (Scheme 1) using catalytic [(neocuproine)PdOAc]2OTf2 (2

Cyclopamine analogs bearing exocyclic methylenes are highly potent and acid-stable inhibitors of hedgehog signaling

• Johann Moschner,
• Anna Chentsova,
• Nicole Eilert,
• Irene Rovardi,
• Philipp Heretsch and
• Athanassios Giannis

Beilstein J. Org. Chem. 2013, 9, 2328–2335, doi:10.3762/bjoc.9.267

• modified F-ring was obtained starting again from azide 3 (see Scheme 1). Reduction of the lactone moiety to give a tetrahydrofuran was accomplished in three steps including (1) partial reduction to the lactol (DIBAl-H, THF, −78 °C to −60 °C, 95%), (2) acetylation (Ac2O, pyridine, cat. DMAP, quant.) and (3

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• between glyoxilic acid monohydrate (3.13) and 1,4-dithiane-2,5-diol (3.14) (Scheme 33) [87]. Subsequent acetylation of the hydroxy group followed by ester formation using (−)-L-menthol permits crystallisation separation of the two diastereoisomers. The use of bis-TBDMS-cytosine as a coupling partner in

Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

• Verena Weidmann,
• Mathias Schaffrath,
• Holger Zorn,
• Julia Rehbein and
• Wolfgang Maison

Beilstein J. Org. Chem. 2013, 9, 2233–2241, doi:10.3762/bjoc.9.262

• been reported with POCl3 in pyridine. Again, this known protocol did not work satisfactory for us resulting in only minor amounts of the desired vitispirane (23). As a consequence, we decided to use an alternative method via acetylation and Pd-catalyzed elimination. This conversion gave vitispirane (23

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• reduction, acetylation and a magnesium sulfate induced rearrangement of the epoxide to the allylic alcohol. The synthesis of cytochalasin B 52 (15 steps from 73) proceeded in a similar fashion and was highlighted in detail by Hertweck [44]. The authors state that this approach is highly diversifiable and

• ]. The synthesis commenced with the preparation of the isoindolinone building block 134. Friedel–Crafts acetylation of 132, followed by a Lieben haloform degradation gave the corresponding acid, which after methylation yielded 133. Bromination and lactam formation afforded isoindolinone 134. The

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

• David Benito-Alifonso,
• Rachel A. Jones,
• Anh-Tuan Tran,
• Hannah Woodward,
• Nichola Smith and
• M. Carmen Galan

Beilstein J. Org. Chem. 2013, 9, 1867–1872, doi:10.3762/bjoc.9.218

• shown by TLC. Thus, the acetamido groups in the oligosaccharides were introduced by first removing the N-Troc protecting group using LiOH in THF at reflux, followed by complete acetylation in pyridine and acetic anhydride. It is important to highlight that the use of activated Zn dust in acetic acid to

• access disaccharide 20b, trichloroacetimidate glycoside donor 12 was reacted with 19 in the presence of catalytic TMSOTf to yield an inseparable mixture of disaccharide product 20a and unreacted starting material. Acetal cleavage with p-TsOH in MeOH under sonication followed by acetylation of the free OH

• cleavage of the 4,6-O-benzylidene acetals using p-TsOH in MeOH under sonication followed by removal of the N-Troc groups in the presence of LiOH and subsequent acetylation with pyridine and acetic anhydride formed the desired acetamido functionalities, removal of the ester groups under basic conditions was

Straightforward synthesis of a tetrasaccharide repeating unit corresponding to the O-antigen of Escherichia coli O16

• Manas Jana and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 1757–1762, doi:10.3762/bjoc.9.203

• separated by chromatography. Spectral analysis of compound 7 confirmed its formation (signals at δ 5.46 (d, J = 3.5 Hz, H-1A), 5.11 (d, J = 3.5 Hz, H-1C), 5.06 (br s, H-1B) and at δ 98.1 (C-1A), 98.0 (C-1B), 92.5 (C-1C) in the 1H and 13C NMR spectra, respectively). The de-O-acetylation of compound 7 by

• transfer hydrogenation with triethylsilane and 10% Pd/C [20]; (b) an acetylation using acetic anhydride and pyridine, and (c) a saponification reaction with sodium methoxide to furnish compound 1, which was purified over a Sephadex® LH-20 gel to give the pure compound 1 in 64% overall yield. The structure

New tridecapeptides of the theonellapeptolide family from the Indonesian sponge Theonella swinhoei

• Annamaria Sinisi,
• Barbara Calcinai,
• Carlo Cerrano,
• Henny A. Dien,
• Angela Zampella,
• Claudio D’Amore,
• Barbara Renga,
• Stefano Fiorucci and
• Orazio Taglialatela-Scafati

Beilstein J. Org. Chem. 2013, 9, 1643–1651, doi:10.3762/bjoc.9.188

• 5.19) with the Me-Ile carbonyl group revealed the presence of an ester linkage. HMBC analysis also revealed that the amide carbonyl at δC 166.5 assigned to the methylsulfinylacetyl subunit was correlated to the Hα of Val-1 residue, thus establishing the acetylation of the N-terminus in 2. Methanolysis

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

• Guillaume Moreira,
• Laurence Charles,
• Mohamed Major,
• Florence Vacandio,
• Yohann Guillaneuf,
• Catherine Lefay and
• Didier Gigmes

Beilstein J. Org. Chem. 2013, 9, 1589–1600, doi:10.3762/bjoc.9.181

• di-tert-butyl nitroxide (DBN) as a control agent (Figure 1). The acetylation of VLA enabled the synthesis of well-defined glycopolymers with molar mass ranging from 2,000 to 40,000 g·mol−1 along with PDI values of about 1.1, whereas the NMP of VLA could not exceed Mn higher than 6,000, with PDI

Design and synthesis of tag-free photoprobes for the identification of the molecular target for CCG-1423, a novel inhibitor of the Rho/MKL1/SRF signaling pathway

• Jessica L. Bell,
• Andrew J. Haak,
• Susan M. Wade,
• Yihan Sun,
• Richard R. Neubig and
• Scott D. Larsen

Beilstein J. Org. Chem. 2013, 9, 966–973, doi:10.3762/bjoc.9.111

• began with the acetylation of 4-chloro-3-nitroaniline (9) followed by reduction of the nitro group using iron and hydrochloric acid to generate aniline 10. The azido group was introduced by diazotization/azidation to provide 11. Deacetylation with potassium hydroxide revealed aniline 12, which was then

Recent progress in the discovery of small molecules for the treatment of amyotrophic lateral sclerosis (ALS)

• Allison S. Limpert,
• Margrith E. Mattmann and
• Nicholas D. P. Cosford

Beilstein J. Org. Chem. 2013, 9, 717–732, doi:10.3762/bjoc.9.82

• gene analysis studies have discovered distinct gene expression profiles in ALS patients [69][70], indicating that transcriptional dysfunction may contribute to ALS pathology [71]. One mechanism of eliciting changes in gene expression is through the acetylation of histone proteins, which allows access

• of gene sequences to transcriptional complexes. SOD1 G93A mice have markedly reduced histone acetylation following disease onset as compared to control animals [71][72], supporting a role for aberrant transcriptional activity in disease progression. Consequently, histone deacetylase (HDAC) inhibitors

• neuromuscular junctions (NMJ) to be analyzed. Treatment with 34 increased histone acetylation in the spinal cord and skeletal muscle of SOD1 G93A mice, which corresponded with reduced motor neuron death and gliosis in the spinal cord of these animals [72]. Additionally, NMJ innervation was improved in mice

Short synthesis of the common trisaccharide core of kankanose and kankanoside isolated from Cistanche tubulosa

• Goutam Guchhait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 705–709, doi:10.3762/bjoc.9.80

• presence of molecular iodine [13] furnished compound 5 in 86% yield. Regioselective 3-O-glycosylation of compound 5 with L-rhamnose derived trichloroacetimidate derivative 3 [11] in the presence of NOBF4 [14] followed by acetylation in the same pot furnished disaccharide derivative 6 in 76% yield. In this

• case, NOBF4 acts as a promoter for the activation of the glycosyl trichloroacetimidate derivative as well as the acetylation of the sugar derivative with acetic anhydride. The formation of compound 6 was confirmed by its spectral analysis [signals at δ 5.44 (s, PhCH), 4.79 (br s, H-1B), 4.37 (d, J

Chemoenzymatic synthesis and biological evaluation of enantiomerically enriched 1-(β-hydroxypropyl)imidazolium- and triazolium-based ionic liquids

• Paweł Borowiecki,
• Małgorzata Milner-Krawczyk and
• Jan Plenkiewicz

Beilstein J. Org. Chem. 2013, 9, 516–525, doi:10.3762/bjoc.9.56

• control the direction of an enzymatic reaction and its specificity in a nonaqueous environment has resulted in the development of so-called "solvent engineering". After testing several solvents for lipase-catalyzed acetylation of (±)-3a and (±)-3b with vinyl acetate, we determined the following order of

• turn, conversion exceeding 57% was beneficial for high optical purity of the remaining alcohol (+)-5a (Table 1, entries 6 and 7, >97% ee). In the lipase-catalyzed acetylation of alcohol (±)-3b the best results were achieved with native Pseudomonas fluorescens lipase (Amano AK) suspended in 2-methyl-2

• acetylation of (±)-3a, the highest reaction rates for (±)-3b were observed with Amano PS-IM in MTBE. As usual, the optical purities of the acetate, as well as of the remaining alcohol, were dependent on the enzyme used and the conversion rate. For example, with Amano AK the reaction reached 37% conversion

Efficient Cu-catalyzed base-free C–S coupling under conventional and microwave heating. A simple access to S-heterocycles and sulfides

• Silvia M. Soria-Castro and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2013, 9, 467–475, doi:10.3762/bjoc.9.50

• and 2i (Table 3, entries 3 and 9). The reaction between 4-iodoaniline and 1 under CuI/1,10-phenanthroline catalysis afforded quantitatively the corresponding 4-iodoacetanilide as the only product. The acetylation of the amino group competes effectively with the cross-coupling reaction. A similar

• acetylation reaction was also observed with 2-iodophenol. In consequence, protected amino and hydroxy groups were required for the copper-mediated C–S bond formation to proceed properly (Table 3, entries 3, 4 and 9). This copper-catalyzed coupling reaction was also applied to heteroaromatic and other

Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

• Alexej Bubnov,
• Miroslav Kašpar,
• Věra Hamplová,
• Ute Dawin and
• Frank Giesselmann

Beilstein J. Org. Chem. 2013, 9, 425–436, doi:10.3762/bjoc.9.45

• acid, ethanol was evaporated, and the aqueous mixture was left to stand in the refrigerator overnight. The crude substance was separated on fritted glass and crystallized from ethanol. Purification of crude phenol 2 was performed after its acetylation: 3 hours boiling with acetanhydride followed by

De novo synthesis of D- and L-fucosamine containing disaccharides

• Daniele Leonori and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 332–341, doi:10.3762/bjoc.9.38

• strategic N-protecting group was evaluated. Direct glycosylation by using the building block D-8a was not possible. Hence, a direct N-Boc deprotection/N-acetylation sequence afforded D-10 in 84% yield (Scheme 6A). Direct glycosylation of D-10 by using glycosylating agent 11 [67] and BF3·Et2O as the

Synthesis and testing of the first azobenzene mannobioside as photoswitchable ligand for the bacterial lectin FimH

• Vijayanand Chandrasekaran,
• Katharina Kolbe,
• Femke Beiroth and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2013, 9, 223–233, doi:10.3762/bjoc.9.26

• , acetylation of the 4- and 6-hydroxy groups, and then acid-mediated regioselective ring opening of the 2,3-orthoester in the same pot to yield the free 3-OH azobenzene mannoside 10 in an overall yield of 43%. Thus, the required protecting group pattern was obtained in a highly efficient way, based on the

• regioselective opening of orthoacetates to yield a vicinal arrangement of equatorial OH and axial O-acetyl groups [21][22]. The acetylation pattern was clearly confirmed by 1H NMR spectroscopy showing the expected downfield shift for the H-3 signal resonating at 4.32 ppm (H-2: 5.30 ppm, H-4: 5.17 ppm). Next

• ). The crude orthoester-protected mannoside 9 (594 mg) was dissolved in pyridine (2.5 mL), and acetic anhydride (1.26 mL) was added for O-acetylation. The reaction mixture was stirred at rt for 3 h. Then, pyridine was removed under reduced pressure, and the residue was dissolved in ethyl acetate (20 mL

Synthesis of 5-(ethylsulfonyl)-2-methoxyaniline: An important pharmacological fragment of VEGFR2 and other inhibitors

• Miroslav Murár,
• Gabriela Addová and
• Andrej Boháč

Beilstein J. Org. Chem. 2013, 9, 173–179, doi:10.3762/bjoc.9.20

• three simple synthetic steps (N-acetylation, O-methylation, N-acetyl deprotection). Later on 2-amino-4-(ethylsulfonyl)phenol was discontinued from current commercial sources. Compound 5 is still available in small 1 g quantities but at a price that was unfavourable (e.g., as part of the AldrichCPR

A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors

• El Sayed H. El Ashry,
• El Sayed H. El Tamany,
• Mohy El Din Abdel Fattah,
• Mohamed R. E. Aly,
• Ahmed T. A. Boraei and
• Axel Duerkop

Beilstein J. Org. Chem. 2013, 9, 135–146, doi:10.3762/bjoc.9.16

• of the N-glycosides 8–10 (Scheme 3) mediated with ammonia in aqueous methanolic solution led to de-O-acetylation of the glycan moieties along with aminolysis of the oxadiazole ring affording 2-N-(glycosyl)thiosemicarbazides 11–13 instead of the corresponding nucleosides 14–16. The oxadiazole ring

• cleavage combined with de-O-acetylation of 8–10 is proven by three facts. First, the molecular weights derived from the mass spectra of the products 11–13 are higher by seventeen atomic mass units than would be those of the deacetylated products 14–16. Second, the IR spectra of 11–13 show new amide

• conditions remained unchanged compared to the cleavage of 8–10, derivatives 26 and 27 (Scheme 6) yielded different products under these conditions. Oxadiazole ring cleavage combined with de-O-acetylation converted 26 into the corresponding 2-N-(glycosyl)thiosemicarbazide 29 while the galactonucleoside 27 was

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

• Mayeul Collot,
• Steffen Eller,
• Markus Weishaupt and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

• avoid neutralization of the activator during glycosylation reactions, unreacted amino groups were capped by acetylation. Resin loadings with the amide-bound linkers 25–29 were determined by using variants including the ester insert for rapid cleavage (Table 1). Glycosylation with monosaccharide building

Thioester derivatives of the natural product psammaplin A as potent histone deacetylase inhibitors

• Matthias G. J. Baud,
• Thomas Leiser,
• Vanessa Petrucci,
• Mekala Gunaratnam,
• Stephen Neidle,
• Franz-Josef Meyer-Almes and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2013, 9, 81–88, doi:10.3762/bjoc.9.11

• epigenetic modifications, their biological outcomes, and how their misregulation is involved in diseases such as cancer [1][2]. The dynamic post-translational acetylation/deacetylation of histone proteins is one of the most commonly studied epigenetic events, and occurs at specific lysine residues on the N

• -terminal histone tails, which project out from the nucleosome (the fundamental repeating unit of chromatin). Acetylation/deacetylation of such lysine residues is achieved by the action of histone acetyltransferases (HATs) and histone deacetylases (HDACs), respectively. Histone deacetylation by HDACs causes

A bisazobenzene crosslinker that isomerizes with visible light

• Subhas Samanta,
• Harris I. Qureshi and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2012, 8, 2184–2190, doi:10.3762/bjoc.8.246

• nitrite with HCl (Scheme 2). Compound 4 was prepared by hydrogenation with H2/Pd-C from sodium 2-acetamido-5-nitrobenzenesulfonate (5), which was obtained from commercially available sodium 2-amino-5-nitrobenzenesulfonate (6) by acetylation using acetic anhydride. 1,4-Diphenylpiperazine (7) was

S-Fluorenylmethyl protection of the cysteine side chain upon N^α-Fmoc deprotection

• Johannes W. Wehner and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2012, 8, 2149–2155, doi:10.3762/bjoc.8.242

• (TES) as cation scavenger [12] yields the O-acetylated glycoamino acid derivative 6 together with its respective disulfide (not shown in Scheme 2), and de-O-acetylation under Zemplén conditions [13] furnishes the unprotected compound 3-dimer after oxidation in air, as reported previously [3]. However

• glycoamino acid derivative 6 was not obtained. De-O-acetylation of 8 gave mannopyranoside 9 with maintained fluorenylmethyl protection at the sulfur atom. The structure of the S-Fm-protected glycoamino acid derivative 8 could be unequivocally confirmed by NMR analysis and MALDI–TOF mass spectrometry. The

Synthesis of a derivative of α-D-Glcp(1->2)-D-Galf suitable for further glycosylation and of α-D-Glcp(1->2)-D-Gal, a disaccharide fragment obtained from varianose

• Carla Marino,
• Carlos Lima,
• Karina Mariño and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2012, 8, 2142–2148, doi:10.3762/bjoc.8.241

• was treated with DSB, as previously reported for other glycosylaldonolactones [10][25][28]. Although lactol 6 was obtained, the reaction was slow and even after several days it was not complete (Scheme 1). Acetylation of the HO-3 of 5 did not improve the reduction step. Certainly, the presence of the

Chemical modification allows phallotoxins and amatoxins to be used as tools in cell biology

• Jan Anderl,
• Hartmut Echner and
• Heinz Faulstich

Beilstein J. Org. Chem. 2012, 8, 2072–2084, doi:10.3762/bjoc.8.233

• chloride (Table 2). In order to avoid concurrent acylation of the 6’-OH of tryptophan, the phenolic OH was methylated before acetylation. For coupling to polylysine the natural carboxy group of aspartic acid as present in β-amanitin was used, which after activation as N-hydroxysuccinimide ester reacted