Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• was much lower (2.6:1 and 1:1, respectively). Acid hydrolysis of 64 gave (4S)-4-hydroxy-L-glutamic acid [(2S,4S)-3] as the hydrochloride, however, its enantiomeric purity was not checked. In connection with the total synthesis of thiopeptide antibiotic nosiheptide an orthogonally protected (4S)-4

• protected 3,4-dihydroxy-L-glutamic acid 96 and the respective γ-lactone 97 formed from 96 in the presence of acids. Benzyl alcohol was selected to refrain from decomposition of the final amino acids during the acid hydrolysis of, e.g., methyl esters [99] since for a mixture of 96 and 97 hydrogenolysis

• pyrrolidine-2-one (3S,4S,5R)-123 [111]. Oxidation of the hydroxymethyl group and acid hydrolysis gave (2S,3S,4S)-4 [112]. By enantioselective conjugate addition and asymmetric dihydroxylation An orthogonally protected 3,4-dihydroxy-L-glutamic acid was envisioned as an intermediate in the projected synthesis

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

Electrochemical Corey–Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone

• Ernesto Emmanuel López-López,
• José Alvano Pérez-Bautista,
• Fernando Sartillo-Piscil and
• Bernardo A. Frontana-Uribe

Beilstein J. Org. Chem. 2018, 14, 547–552, doi:10.3762/bjoc.14.41

• 6 was prepared in two steps from pyrone dioxolane 7 [7]. Acid hydrolysis of 7 to 1,2-diol 8 followed by the reaction with 1,1’-thiocarbonyldiimidazole afforded thiocarbonate precursor 6 in high overall yield (Scheme 3). Compounds 6 and 8 were prepared in a similar manner as described in reference [7

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• Grignard reagent through two possible pathways. As indicated by the blue arrow in Scheme 3, when vinylmagnesium chloride attacks the carbonyl carbon of Int-I, the corresponding adduct Int-K is formed in situ; this adduct can be smoothly converted into the desired octa-1,7-diene 5a after acid hydrolysis. On

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• ]nonadienes (bisdioxines) 4. When arylamines are used as the nucleophiles under neutral conditions, decarboxylation occurs during the formation of bisdioxines 8. However, when water or alcohols are added to 3 under acidic conditions, bisdioxine-carboxylic acids and esters 10 and 11 are obtained. Acid

• hydrolysis of the bisdioxines proceeds through the addition of water to a C=C double bond and results in a second transannular oxa-Michael-type reaction and generation of tetraoxaadamantanes 5. This reaction is decarboxylative when free carboxylic acid functions are present in the bisdioxines, thus forming

The synthesis of the 2,3-difluorobutan-1,4-diol diastereomers

• Robert Szpera,
• Nadia Kovalenko,
• Kalaiselvi Natarajan,
• Nina Paillard and
• Bruno Linclau

Beilstein J. Org. Chem. 2017, 13, 2883–2887, doi:10.3762/bjoc.13.280

• using PyFluor only led to the formation of the 2-pyridinesulfonate intermediate (±)-12, the use of DAST at 60 °C proved successful. The difluoride meso-11 was not isolated due to its low boiling point, but was immediately subjected to acid hydrolysis to give anti-5. Unfortunately, the yield for this two

Aqueous semisynthesis of C-glycoside glycamines from agarose

• Juliana C. Cunico Dallagnol,
• Alexandre Orsato,
• Diogo R. B. Ducatti,
• Miguel D. Noseda,
• Maria Eugênia R. Duarte and
• Alan G. Gonçalves

Beilstein J. Org. Chem. 2017, 13, 1222–1229, doi:10.3762/bjoc.13.121

• -containing oligosaccharides from 1 by acid hydrolysis, it is important to notice that the 3,6-anhydrogalactosidic bonds are more acid labile than most of pyranoses. In this way, if AnGal is not produced as a free monosaccharide, it is found as the reducing terminal of the resulting oligosaccharides. Due to

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• formation of lactone 111 and subsequent acid hydrolysis to give 107f. At the third stage (route A), ether 112 is formed from 110 and subsequently rearranged by a Baeyer–Villiger reaction into 113, which is oxidized to form 106f. This method can be applied to the synthesis of dodecanedioic acid, which is

Marine-derived myxobacteria of the suborder Nannocystineae: An underexplored source of structurally intriguing and biologically active metabolites

• Antonio Dávila-Céspedes,
• Peter Hufendiek,
• Max Crüsemann,
• Till F. Schäberle and
• Gabriele M. König

Beilstein J. Org. Chem. 2016, 12, 969–984, doi:10.3762/bjoc.12.96

• miuraenamide A (31) the absolute configuration was determined. Marfey´s method was employed to show that L-alanine and N-methyl-D-tyrosine are present. Furthermore, after acid hydrolysis, methylation and application of modified Mosher´s method the absolute configuration at the oxygen bearing C-9 was deduced as

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• hydantoins 24–26). On the other hand, acid hydrolysis of these adducts efficiently affords N-alkylamino acid derivatives, as for instance the N-methylamino amide 21. Additionally, from the common adduct 26, functionalized polycyclic hydantoins of type 27 and 28 can also be synthesized. The authors proposed

Elucidation of a masked repeating structure of the O-specific polysaccharide of the halotolerant soil bacteria Azospirillum halopraeferens Au4

• Elena N. Sigida,
• Yuliya P. Fedonenko,
• Alexander S. Shashkov,
• Nikolay P. Arbatsky,
• Evelina L. Zdorovenko,
• Svetlana A. Konnova,
• Vladimir V. Ignatov and
• Yuriy A. Knirel

Beilstein J. Org. Chem. 2016, 12, 636–642, doi:10.3762/bjoc.12.62

• , Russia N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospekt 47, Moscow 119991, Russia Chernyshevsky Saratov State University, Ulitsa Astrakhanskaya 83, Saratov 410012, Russia 10.3762/bjoc.12.62 Abstract An O-specific polysaccharide was obtained by mild acid

• hydrolysis of the lipopolysaccharide isolated by the phenol–water extraction from the halotolerant soil bacteria Azospirillum halopraeferens type strain Au4. The polysaccharide was studied by sugar and methylation analyses, selective cleavages by Smith degradation and solvolysis with trifluoroacetic acid

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• R1 and R2. In both cases, a second electron reduction in presence of CO2 yields a carboxylate intermediate with an additional carbonate or carbamate group. The latter is converted to the corresponding α-hydroxy acid or to an α-amino acid after acid hydrolysis in the product work-up [75][76][77]. An

• , the gradual consumption of the anode material is a major drawback for industrial applications. Not only is it rather expensive to consume such large amounts of metal; it also strongly hinders the implementation of a continuous process. Additionally, in order to obtain the free acids, an acid

• hydrolysis step is required, complicating product purification, and generating a significant amount of waste. The potential industrial use of electrochemical CO2 fixation with sacrificial anodes should be found in fine chemical applications, preferably when the carboxylate salt can be used as such

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions

• Andrea Caporale,
• Stefano Tartaggia,
• Andrea Castellin and
• Ottorino De Lucchi

Beilstein J. Org. Chem. 2014, 10, 384–393, doi:10.3762/bjoc.10.36

• symmetrical acetylene. Finally, it is worth noting that the preparation of product 2a has been also reported through the acid hydrolysis of the acetamido group of 2b or by the reduction of the nitro group of 2o [76], however the direct coupling of 3-bromoaniline with 4 or 6 clearly remains the most efficient

Bis(benzylamine) monomers: One-pot preparation and application in dendrimer scaffolds for removing pyrene from aqueous environments

• Olivia N. Monaco,
• Sarah C. Tomas,
• Meghan K. Kirrane and
• Amy M. Balija

Beilstein J. Org. Chem. 2013, 9, 2320–2327, doi:10.3762/bjoc.9.266

• ambient conditions in air over four months but degraded to release benzaldehyde within two hours in CHCl3, CH2Cl2, and THF as noted by the red shift in the UV–vis absorption spectrum. 1H NMR spectroscopic analysis confirmed the disappearance of the imine peak upon exposure of bisimine 3 to acid

• . Hydrolysis occurred at different rates with varying functionalities on 3; however, a quantitative comparison of how the substituents affected hydrolysis could not be adequately obtained. Bisamine 4 was found to be more stable in air although it began to decompose after exposure to organic solvents for one

Synthesis of enantiomerically pure (2S,3S)-5,5,5-trifluoroisoleucine and (2R,3S)-5,5,5-trifluoro-allo-isoleucine

• Holger Erdbrink,
• Elisabeth K. Nyakatura,
• Susanne Huhmann,
• Ulla I. M. Gerling,
• Dieter Lentz,
• Beate Koksch and
• Constantin Czekelius

Beilstein J. Org. Chem. 2013, 9, 2009–2014, doi:10.3762/bjoc.9.236

• sodium cyanide to afford nitrile 3. Acid hydrolysis of 3 provided the enantiomerically pure carboxylic acid (R)-4 [19], which was then coupled to the oxazolidinone via the mixed anhydride (Scheme 1). With N-acyloxazolidinone 5 in hand, the optically active fluorinated α-amino acids (L-5,5,5

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

• presence of the b2 fragmentation peak at m/z 331 supported, once again, the presence of the MeS(O)Ac unit. Complete acid hydrolysis of 2 and Marfey’s analysis [21] on the hydrolysate (derivatization with L-FDAA, 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide, followed by LC–MS comparison with the FDAA

• (positions 5–10 and 28–32) with valine residues. Complete acid hydrolysis of 3 and Marfey’s analysis [21] on the hydrolysate mixture provided the configuration of the chiral amino acid residues as L-MeAla, D-Leu (×2), D-MeLeu, L-Thr, L-Me-Ile, D-Me-Val, D-Val, L-Me-Val and L-Val. With these data in hands, it

• ; found, 1444.8834. Theonellapeptolide If (3): Colorless amorphous solid; [α]D25 −26.7 (c 0.1, CH3OH); 1H and 13C NMR data in CD3OD are given in Table 2; ESIMS (m/z): 1377 [M + H]+ and 1399 [M + Na]+. HRMS–ESI (m/z): [M + Na]+ calcd for C69H121N13NaO16, 1398.8952; found, 1398.8949. Acid hydrolysis and

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

• ) were reported and the grafted PS chains, analysed by SEC after acid hydrolysis of the cellulose backbone, proved to be efficient to control the polymerization (number-average molar mass Mn ranging from 28,000 to 62,000 g·mol−1 and polydispersity index PDI ranging from 1.28 to 1.52). To our knowledge

Methylidynetrisphosphonates: Promising C₁ building block for the design of phosphate mimetics

• Vadim D. Romanenko and
• Valery P. Kukhar

Beilstein J. Org. Chem. 2013, 9, 991–1001, doi:10.3762/bjoc.9.114

• subjected to acid hydrolysis. Thus, although the bisphosphonate PhCH2CH(PO3Et2)2 smoothly undergoes hydrolysis to the corresponding bisphosphonic acid by treatment with HCl under reflux, benzyltrisphosphonate PhCH2C(PO3Et2)3 undergoes dephosphonylation under similar conditions [25][26]. Synthesis of free

Development of peptidomimetic ligands of Pro-Leu-Gly-NH₂ as allosteric modulators of the dopamine D₂ receptor

• Swapna Bhagwanth,
• Ram K. Mishra and
• Rodney L. Johnson

Beilstein J. Org. Chem. 2013, 9, 204–214, doi:10.3762/bjoc.9.24

• oxazolidinones 56 and 57, which served as precursors to the corresponding novel (R,R)-α,α’-biproline 58 and meso-α,α’-biproline 59 [57]. In contrast, the reaction of the more electrophilic alkylating agent glycol bistriflate with the enolate of 30 provided the desired dimer 55, which after acid hydrolysis of 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

• contains galactofuranose (Galf) in both α and β-configurations in the repeating unit (Figure 1). Further studies established that the galactofuran of alternating β(1→6) and β(1→5)Galf units is branched at the O-2 of the (1→5)-linked Galf with the disaccharide α-D-Glcp(1→2)-α-D-Galf [4]. Mild acid

• hydrolysis, which preferentially cleaves the furanosidic linkages, allowed the isolation and characterization of the disaccharide with the reducing galactose isomerized to the more stable pyranose form. The same disaccharide unit is present in the cell-wall polysaccharide of Talaromyces flavus [5] and in the

Convergent synthesis of the tetrasaccharide repeating unit of the cell wall lipopolysaccharide of Escherichia coli O40

• Abhijit Sau and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2012, 8, 2053–2059, doi:10.3762/bjoc.8.230

• isopropylidene ketal and benzylidene acetal by acid hydrolysis; and finally (d) removal of benzyl ethers by using triethylsilane and 20% Pd(OH)2–C [20] to furnish target compound 1, which was purified through a Sephadex® LH-20 column to give pure compound 1 in 60% overall yield. Spectral data of compound 1

A novel asymmetric synthesis of cinacalcet hydrochloride

• Veera R. Arava,
• Laxminarasimhulu Gorentla and
• Pramod K. Dubey

Beilstein J. Org. Chem. 2012, 8, 1366–1373, doi:10.3762/bjoc.8.158

• alcohol intermediate 12 from 10. Synthesis of bromo 5 and iodo 6 derivatives. Regioselective N-alkylation of naphthyl ethyl sulfinamide 4a. Acid hydrolysis of N-tert-butanesulfinyl group in 7. Screening of reduction conditions (9→10). Conditions for regioselective N-alkylation of naphthylethylsulfinamide

Triterpenoid saponins from the roots of Acanthophyllum gypsophiloides Regel

• Elena A. Khatuntseva,
• Vladimir M. Men’shov,
• Alexander S. Shashkov,
• Yury E. Tsvetkov,
• Rodion N. Stepanenko,
• Raymonda Ya. Vlasenko,
• Elvira E. Shults,
• Genrikh A. Tolstikov,
• Tatjana G. Tolstikova,
• Dimitri S. Baev,
• Vasiliy A. Kaledin,
• Nelli A. Popova,
• Valeriy P. Nikolin,
• Pavel P. Laktionov,
• Anna V. Cherepanova,
• Tatiana V. Kulakovskaya,
• Ekaterina V. Kulakovskaya and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2012, 8, 763–775, doi:10.3762/bjoc.8.87

• , consistent with the molecular formula С75H118O39. GLC analysis of the acetylated (S)-2-octyl glycosides derived after full acid hydrolysis of compound 1 revealed the presence of D-galactose (D-Gal), L-arabinose (L-Ara), 6-deoxy-D-glucose (D-Qui), D-xylose (D-Xyl), L-rhamnose (L-Rha), D-fucose (D-Fuc), and D

Synthesis of functionalized macrocyclic derivatives of trioxabicyclo[3.3.0]nonadiene

• Sabine Leber,
• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2012, 8, 738–743, doi:10.3762/bjoc.8.83

• concave, axially chiral [1], bridged bisdioxine diacid dichloride 3 is obtained by acid hydrolysis and subsequent chlorination of the surprisingly stable α-oxoketene 2, itself obtained by dimerization of dipivaloylketene (1) (Scheme 1) [2][3]. The concave structure of 3 and its derivatives together with

• reduced nitro derivative 12 as an impurity (Scheme 3). A remarkable reaction is the ready conversion of macrocyclic as well as open-chain bisdioxine derivatives to 2,4,6,8-tetraoxaadamantanes on acid hydrolysis [4][7][15]. This transformation was also achieved with the dinitro compound 8, which yielded