Cross metathesis-mediated synthesis of hydroxamic acid derivatives

• Shital Kumar Chattopadhyay,
• Subhankar Ghosh and
• Suman Sil

Beilstein J. Org. Chem. 2018, 14, 3070–3075, doi:10.3762/bjoc.14.285

• ], separately. Fortunately, both the reactions proceeded well and the desired amino acid derivatives 7k and 7l were obtained in good yields after hydrogenation. Conclusion In conclusion, we have developed a direct access to functionalized hydroxamic acid derivatives using a cross-metathesis reaction between N

N-Acylated amino acid methyl esters from marine Roseobacter group bacteria

• Hilke Bruns,
• Lisa Ziesche,
• Nargis Khakin Taniwal,
• Laura Wolter,
• Thorsten Brinkhoff,
• Jennifer Herrmann,
• Rolf Müller and
• Stefan Schulz

Beilstein J. Org. Chem. 2018, 14, 2964–2973, doi:10.3762/bjoc.14.276

• other amino acid derivatives reported here. We suggest the term NABME (N-acylated 2-aminobutyric acid methyl esters) for the new compounds that can thus be assigned as C16:0-NABME (7) and Z9-C16:1-NABME (8). Compound N showed a mass spectrum (Figure 4c) featuring characteristic ions at m/z 72, 132, and

• preparation Conclusion We have identified here new classes of acylated amino acid derivatives including previously unknown glycine and 2-aminobutyric acid derived compounds. The combination of GC/MS, HPLC/MS, retention indices and synthesis proved to be especially suited to structurally identify minor

• component within the broad peak. Mass spectra of natural compounds a) R (11, C16:1-NAGME) and b) S (10, C16:0-NAGME). EI mass spectrometric fragmentation of N-acylated amino acid derivatives. The ions w–z allow identification of the respective amino acid residue. MS2 spectra in ESI positive mode of a) Z9

Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers

• Zsanett Benke,
• Melinda Nonn,
• Márton Kardos,
• Santos Fustero and
• Loránd Kiss

Beilstein J. Org. Chem. 2018, 14, 2698–2707, doi:10.3762/bjoc.14.247

• derived from cyclodienes were used as starting substances for further functionalization with ROM. We have described a stereocontrolled synthetic route to access difunctionalized cyclic β-amino acid derivatives [14] and β-lactams [15][16] based on ring-opening metathesis (ROM) through ethenolysis of the

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• . found the direct carboxylation reaction with CO2 under photo-irradiation reaction conditions [46]. Jamison et al. also reported the synthesis of α-amino acid derivatives using amine and CO2 [47]. Iwasawa disclosed the Pd-catalyzed carboxylation of aryl halides using CO2 in the presence of an Ir photo

Thiocarbonyl-enabled ferrocene C–H nitrogenation by cobalt(III) catalysis: thermal and mechanochemical

• Santhivardhana Reddy Yetra,
• Zhigao Shen,
• Hui Wang and
• Lutz Ackermann

Beilstein J. Org. Chem. 2018, 14, 1546–1553, doi:10.3762/bjoc.14.131

• using amino acid derivatives, albeit as of yet in a racemic fashion (Table 1, entries 4–7). Yet, optimal catalytic performance was realized with 1-AdCO2H (Table 1, entries 8 and 9) [101][102][103][104], particularly when using DCE as the solvent (Table 1, entries 9–12). A control experiment verified the

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• asymmetric alkylation of tert-butyl glycinate benzophenone Schiff base 3 with alkyl halides 4 in a toluene–50% KOH biphasic system (Scheme 1). The corresponding α-alkyl-α-amino acid derivatives 5 were obtained in excellent yields with very low enantioselectivities (up to 9%). This is the first example of

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• acid derivatives) with potassium bromate or Oxone (2KHSO5/KHSO4/K2SO4) efficiently delivered the I(V) reagents 4 (Scheme 2c) [28][29]. Although good product yields were obtained for the oxidation of sulfides, the ees were very low. New classes of chiral hypervalent iodine reagents were obtained by the

• sulfides to sulfoxides with good yields but with poor enantioselectivity (Scheme 2b) [27]. Later, Zhdankin et al. synthesized different classes of chiral I(V) reagents 4 based on various amino acids as sources of chirality. The oxidation of the readily available 2-iodobenzamides (synthesized from amino

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

• Sabine Schuster,
• Beáta Biri-Kovács,
• Bálint Szeder,
• Viktor Farkas,
• László Buday,
• Zsuzsanna Szabó,
• Gábor Halmos and
• Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64

• conjugates targeting GnRH receptors in human cancers. Experimental Material All amino acid derivatives and Rink-Amide MBHA resin were purchased from Iris Biotech GmBH (Marktredwitz, Germany). Boc-aminooxyacetic acid (Boc-Aoa-OH), aminooxyacetic acid, scavengers, coupling agents and cleavage reagents (1

• ) followed by ligation of Dau (oxime bond) in solution. All peptides were synthesized manually by usage of the following Fmoc-protected amino acid derivatives: Fmoc-Gly-OH, Fmoc-Pro-OH, Fmoc-Lys(Mtt)-OH, Fmoc-Lys(Dde)-OH, Fmoc-Trp-OH, Fmoc-D-Trp-OH, Fmoc-Asp(Ot-Bu)-OH, Fmoc-D-Asp(Ot-Bu)-OH, Fmoc-D-Glu(Ot-Bu

Recent developments in the asymmetric Reformatsky-type reaction

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 325–344, doi:10.3762/bjoc.14.21

• trifluoromethyl group. It must be noted that this methodology represented the first efficient and general preparation of chiral β-trifluoromethyl β-amino acid derivatives containing a quaternary stereocenter adjacent to the amine function. In 2014, Linclau and Poisson reported the synthesis of chiral α,α-difluoro

• been described using chiral reagents. For example, the first efficient synthesis of chiral β-trifluoromethyl β-amino acid derivatives containing a quaternary stereocenter adjacent to the amine function has been reported with up to >98% de through diastereoselective Zn-mediated aza-Reformatsky reactions

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• linear and branched primary, secondary and aromatic thiols react with linear and substituted aliphatic alkenes and styrenes. Due to the high functional group tolerance, they demonstrated the applicability to the preparation of glycoconjugates from glycosyl thiols and amino acid derivatives. They propose

Quinone-catalyzed oxidative deformylation: synthesis of imines from amino alcohols

• Xinyun Liu,
• Johnny H. Phan,
• Benjamin J. Haugeberg,
• Shrikant S. Londhe and
• Michael D. Clift

Beilstein J. Org. Chem. 2017, 13, 2895–2901, doi:10.3762/bjoc.13.282

• this reaction sequence, (thio)silyl ketene acetal 10 was united with 2-phenylglycinol and para-anisidine in a two-step, one-pot process to provide β-amino acid derivative 11 in a 60% yield. The overall reaction sequence provides a unique method for the production of the high-value β-amino acid

• derivatives [49][50] from 1,2-amino alcohols. Conclusion In conclusion, we have developed a novel method for the synthesis of imines from 1,2-amino alcohols. This chemistry features an unprecedented application of quinone organocatalysis to enable oxidative deformylation under aerobic conditions. Future work

A Brønsted base-promoted diastereoselective dimerization of azlactones

• Danielle L. J. Pinheiro,
• Gabriel M. F. Batista,
• Pedro P. de Castro,
• Leonã S. Flores,
• Gustavo F. S. Andrade and
• Giovanni W. Amarante

Beilstein J. Org. Chem. 2017, 13, 2663–2670, doi:10.3762/bjoc.13.264

• -position of α-amino acid derivatives. To this end, different catalytic transformations involving azlactones have been established [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For example, our research group has explored the potential of these heterocycles in the presence of Michael

Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1H)-ones

• Sergii V. Melnykov,
• Andrii S. Pataman,
• Yurii V. Dmytriv,
• Svitlana V. Shishkina,
• Mykhailo V. Vovk and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2017, 13, 2617–2625, doi:10.3762/bjoc.13.259

• malonic acid and its mono(thio)esters have been poorly investigated so far despite the potential to become a convenient route to β-trifluoromethyl-β-amino acid derivatives and to their partially saturated heterocyclic analogues. Results: In this paper we show that 4-trifluoromethylpyrimidin-2(1H)-ones

Synthesis of 1,3-cis-disubstituted sterically encumbered imidazolidinone organocatalysts

• Jan Wallbaum and
• Daniel B. Werz

Beilstein J. Org. Chem. 2017, 13, 2577–2583, doi:10.3762/bjoc.13.254

• naturally occurring L-amino acid derivatives. During the condensation process two diastereomers can be formed with the substituents in either a 1,3-cis or 1,3-trans arrangement. Since our reaction design of the above-mentioned reaction (depicted in Scheme 1b) showed a strong preference to use the 1,3-cis

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

• example XtalFluor, Et3N·HF, and pyridine·HF and applying an efficient approach earlier developed by our group, proved to be unsuccessful ([18] and references cited therein). Due to the biological relevance of six-membered β-amino acid derivatives (e.g., tilidin, oryzoxymicin, BAYY9379) [19], we continued

A mechanochemical approach to access the proline–proline diketopiperazine framework

• Nicolas Pétry,
• Hafid Benakki,
• Eric Clot,
• Pascal Retailleau,
• Farhate Guenoun,
• Fatima Asserar,
• Chakib Sekkat,
• Thomas-Xavier Métro,
• Jean Martinez and
• Frédéric Lamaty

Beilstein J. Org. Chem. 2017, 13, 2169–2178, doi:10.3762/bjoc.13.217

• . Subsequently, the mechanocoupling of hindered proline amino acid derivatives was developed to provide proline–proline dipeptides under solvent-free conditions. A deprotection–cyclization sequence yielded the corresponding diketopiperazines that were obtained with a high stereoselectivity which could be

• ][24][25][27] to prepare the Pro–Pro dipeptide from the corresponding amino acid derivatives. We investigated the coupling of proline N-hydroxysuccinimide ester with proline methyl ester in a vibrating ball mill (vbm, Scheme 2) [23]. Surprisingly, while the coupling of various other amino acids

• respectively Boc–Pro–OSu and HCl·H–Pro–OMe. In both cases, the reaction proceeded smoothly to give good yields of dipeptides 3 and 4 (95% of Boc–Pro–Phe–OMe and 82% of Boc–Phe–Pro–OMe, respectively). Most probably, this method was less adapted to hindered amino acid derivatives such as proline. As an

Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

• Spyros D. Chatziefthimiou,
• Mario Inclán,
• Petros Giastas,
• Athanasios Papakyriakou,
• Konstantina Yannakopoulou and
• Irene M. Mavridis

Beilstein J. Org. Chem. 2017, 13, 1572–1582, doi:10.3762/bjoc.13.157

• -CD (Scheme 1) in an effort to contribute to the study of chiral recognition of amino acid derivatives by CDs in the crystalline state and in solution. The guest NAcTrp has been selected because of its large aromatic side chain with appropriate dimensions to fit tightly in the β-CD cavity thus

1-Imidoalkylphosphonium salts with modulated C_α–P⁺ bond strength: synthesis and application as new active α-imidoalkylating agents

• Jakub Adamek,
• Roman Mazurkiewicz,
• Anna Węgrzyk and
• Karol Erfurt

Beilstein J. Org. Chem. 2017, 13, 1446–1455, doi:10.3762/bjoc.13.142

• side reactions (for example Kolbe-dimerization), the yields were only poor (10–35%) [33][34]. According to our previously reported procedure for the electrochemical decarboxylative α-methoxylation of N-acyl-α-amino acids [18], amino acid derivatives 6 were converted to N-(1-methoxyalkyl)imides 7. The

Conformational study of L-methionine and L-cysteine derivatives through quantum chemical calculations and ³J_HH coupling constant analyses

• Weslley G. D. P. Silva,
• Carolyne B. Braga and
• Roberto Rittner

Beilstein J. Org. Chem. 2017, 13, 925–937, doi:10.3762/bjoc.13.94

• atoms in molecules (QTAIM) and noncovalent interactions (NCI) methodologies, the conformational preferences for the compounds are not dictated by intramolecular hydrogen bonding, but by a joint contribution of hyperconjugative and steric effects. Keywords: amino acid derivatives; conformational

• calculations, such as the Møller–Plesset (MP2) method and density functional theory (DFT) calculations, together with experimental techniques have been combined to achieve more accurate results [20][21][22][23][24]. Some amino acid derivatives have been recently studied by our research group, including the

• shown good results for other amino acid derivatives, when comparing theoretical with experimental data [22][23][24]. Although 2 could not be experimentally studied, the theoretical calculations carried out strongly suggest that the conformational equilibrium of 2 and the populations of its conformers

TMSBr-mediated solvent- and work-up-free synthesis of α-2-deoxyglycosides from glycals

• Mei-Yuan Hsu,
• Yi-Pei Liu,
• Sarah Lam,
• Su-Ching Lin and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2016, 12, 1758–1764, doi:10.3762/bjoc.12.164

• -butanol (16), 5-azidopentanol (17), cyclohexanol (18) and 2-adamantanol (19), to give O-2-deoxyglucosides in high yields (74–90%) and α-selectivities (α:β = 7–10:1, Table 3, entries 2–8). Regarding the glycosylation with amino acid derivatives, L-serine 20 and threonine derivative 21, increased ratio of β

• our study, the glycosylation of per-O-acetylated glucal 1 with aliphatic alcohols 12–19 showed better α-selectivities as compared to the per-O-benzylated glucal 3. However, with amino acid derivatives 20 and 21 and monosaccharides 22–24 as acceptors, similar α-selectivities were attained with both

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• synthetic manipulations. Furthermore, enantioselective conjugate additions to α-amino-α,β-unsaturated esters provides rapid access to enantioenriched α-amino acid derivatives. However, α,β-unsaturated esters present some challenges; the transient enolate intermediate can adopt E- or Z-enolate geometries

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• biologically interesting β-amino acid derivatives (Table 2) [42]. In this work, the authors compared the results achieved by means of 4 with other urea- and thiourea-based organocatalysts in order to understand the effect of the acidity, the structural rigidity, and the bifunctionality of the promoter. These

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• ) in the α-hydroxylation of indenones (where n = 1 in 77) using cumyl hydroperoxide (Scheme 19) [58]. Interestingly, the 3,4-dihydronaphthalen-1(2H)-one derivative (where n = 2 in 77) did not afford any detectable product. Transamination A range of α-amino acid derivatives have been accessed by Shi and

Asymmetric α-amination of β-keto esters using a guanidine–bisurea bifunctional organocatalyst

• Minami Odagi,
• Yoshiharu Yamamoto and
• Kazuo Nagasawa

Beilstein J. Org. Chem. 2016, 12, 198–203, doi:10.3762/bjoc.12.22

• important synthetic route to optically active α-amino acid derivatives with chiral quaternary stereocenters [1][2]. Since an α-amino acid moiety is frequently found in biologically active compounds, considerable efforts have been made to achieve a stereoselective synthesis of this structure [3][4]. In

Novel stereocontrolled syntheses of tashiromine and epitashiromine

• Loránd Kiss,
• Enikő Forró and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2015, 11, 596–603, doi:10.3762/bjoc.11.66

• pyrrole, followed by saturation [37]. The transformation of chiral functionalized pyrrole or pyrrolidine derivatives has served as the basis of the construction of (−)-epitashiromine [38][39] (Figure 4). The oxidative functionalization of cyclic β-amino acid derivatives has been reported to be a

• convenient route for the preparation of N-heterocyclic β-amino acid derivatives [40][41] or for the stereocontrolled synthesis of functionalized cispentacins [42] and their acyclic counterparts [43][44] (Figure 5). The oxidative ring cleavage of various vicinal diols and the transformation of the resulting