Safe and highly efficient adaptation of potentially explosive azide chemistry involved in the synthesis of Tamiflu using continuous-flow technology

• Cloudius R. Sagandira and
• Paul Watts

Beilstein J. Org. Chem. 2019, 15, 2577–2589, doi:10.3762/bjoc.15.251

• continuous-flow technology. The two steps involving azide chemistry in flow are reported herein (Scheme 2), with the vision of further integrating the other steps towards continuous-flow total synthesis of this drug. To this effect, we have already reported continuous flow shikimic acid (3) esterification

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• synthesized via an esterification reaction starting from symmetrical 1,1’-ferrocenoyl dichloride (3) [92] as shown in Scheme 1. To a solution of the corresponding 1-alkynol (13.5 mmol), NEt3 (13.5 mmol), and 4-dimethylaminopyridine (DMAP, 0.5 mmol) in dichloromethane (DCM, 20 mL) at 0 °C the dichloride 3 (2 g

• positions of the THF molecules are shown. Selected bond lengths [Å] and angles [°] are given in Supporting Information File 1, Tables S1 and S2. Synthesis of substrates 1 (a n = 2; b n = 3) via esterification of 3 and following RCAM with catalyst MoF6 to ferrocenophanes 2 (a: n = 2; b: n = 3); a) HO(CH2)nC

Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• ligands. The reaction with pinacolborane (HB(pin)) gave ester 9 in 97% yield [11]. Another ester (10) was synthesized by bromination of 3-thiopheneacetic acid with NBS (applying an ultrasound bath) followed by esterification of the crude product with methanol in the presence of sulfuric acid [12]. Other

Genome mining in Trichoderma viride J1-030: discovery and identification of novel sesquiterpene synthase and its products

• Xiang Sun,
• You-Sheng Cai,
• Yujie Yuan,
• Guangkai Bian,
• Ziling Ye,
• Zixin Deng and
• Tiangang Liu

Beilstein J. Org. Chem. 2019, 15, 2052–2058, doi:10.3762/bjoc.15.202

• represent the esterification reaction during the extraction process. The 5/6 bicyclic sesquiterpene identified and characterised in this study was a brasilane-type sesquiterpenoid; this sesquiterpenoid type is typically isolated from cultures of the basidiomycete Coltricia sideroides in combination with its

• characterised as a 5/6 bicyclic sesquiterpene compound 1 oxygenated at C-11. Interestingly, esterified compound 1 was isolated during the product extraction process, suggesting an esterification reaction. It contained a quaternary carbon with two methyl groups, which is uncommon of the cyclization mechanism of

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• of a C–C bond followed by formation of a new C–N/C–O bond in the presence of K2CO3. Various pyridinium salts of phenacyl bromides can be readily transformed into a variety of amides and esters which is an alternative method for the conventional amidation and esterification in organic synthesis. High

• functional group tolerance, broad substrate scope and operational simplicity are the prominent advantages of the current protocol. Keywords: amidation; benzoylation; benzylamines; pyridinium salt of phenacyl bromides; Introduction Amidation and esterification are fundamental transformations in synthetic

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• ][60]. They have been employed for a number of organic reactions viz., hydrosilylation of aldehydes and ketones, acetylation reactions, redox reactions, oxidative esterification, etc. [61][62][63]. Thus, in concern with increasing demand for sustainable development, a growing number of catalytic

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• simply prepared from the commercially available 27 by esterification in ethanol. Cyclization or oligomerization of 27 was not an issue for the transformation. The primary alcohol of 28 was selectively tritylated with DMTrCl to give 29, which was phosphitylated with 13 in the presence of 14 to give 26a

Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

• Marius Kunkel and
• Sebastian Polarz

Beilstein J. Org. Chem. 2019, 15, 901–905, doi:10.3762/bjoc.15.87

• modified, are well known in the literature. These reactions can be achieved by esterification or etherification [20][21][22]. However, partial modifications are rare, especially when it comes to asymmetric substitutions [23][24]. Although, janus-type fullerenols at which only a part of the fullerene core

Synthesis of a novel category of pseudo-peptides using an Ugi three-component reaction of levulinic acid as bifunctional substrate, amines, and amino acid-based isocyanides

• Maryam Khalesi,
• Azim Ziyaei Halimehjani and
• Jürgen Martens

Beilstein J. Org. Chem. 2019, 15, 852–857, doi:10.3762/bjoc.15.82

• esterification of the α-amino acid using thionyl chloride in methanol as reagent and solvent. The second reaction is the formylation of the corresponding amino acid ester salt with ethyl formate in the presence of NaHCO3. Finally, the formamide group was transformed to the corresponding isocyanide 3 using POCl3

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• by epoxide ring-opening and esterification reactions with fatty acids 3 (Scheme 1). If successful, developing a multistep approach to prepare DAGs would contribute to the expansion of synthetic mechanochemical methodologies in ball mills [28][29][30][31], which are often limited to single-step

• esterification reactions by ball milling [44]. In practice, we milled a mixture of MAG 4a, stearic acid (3a), DCC and 4-dimethylaminopyridine (DMAP) at 25 Hz for 2 h in a mixer mill. Separation of the product by column chromatography gave DAG 5a in 97% yield (Scheme 4). Alternatively, 5a could be prepared

• following a one-pot two-step approach in the ball mill by beginning with the cobalt-catalyzed epoxide-ring opening of 2 with 3a, followed immediately by the esterification of the corresponding MAG 4a with stearic acid (3a), DCC and DMAP. Although successful, this strategy led to DAG 5a in lower yield (50

Solid-phase synthesis of biaryl bicyclic peptides containing a 3-aryltyrosine or a 4-arylphenylalanine moiety

• Iteng Ng-Choi,
• Àngel Oliveras,
• Lidia Feliu and
• Marta Planas

Beilstein J. Org. Chem. 2019, 15, 761–768, doi:10.3762/bjoc.15.72

• 9-fluorenylmethoxycarbonyl (Fmoc)/tert-butyl (t-Bu) strategy (Scheme 2). The non-commercially available amino acids Boc-Phe(4-BPin)-OH, Fmoc-Phe(4-I)-OH and Fmoc-Glu-OpNB were prepared in solution. Boc-Phe(4-BPin)-OH was obtained from Boc-Phe(4-I)-OH [27] through esterification, Miyaura borylation

Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• recent synthesis of plusbacin A3, Ichikawa et al. experienced similar difficulties when attempting esterification of a bulky β-OTIPS-substituted amino acid with a secondary alcohol under a variety of conditions [49]. Conclusion We developed a short synthesis of the polyketide building block present in

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• the N1 atom of Nam occurs under these conditions. Hydrolytic de-esterification of 9a,b was achieved by a treatment with an anhydrous ammonia methanolic solution at −5 °C. Removal of benzoyl groups required prolonged reaction times (48 h versus 6 h for acetyl groups). It should be also noted that in

• after de-esterification of the tribenzoate intermediate ( +25°) using methanol saturated with dry ammonia at 2 °C for 2 days (content of β-anomer was <3%, as determined by enzymatic analyses). This result may be explained by the fact that 2,3,5-tri-O-benzoyl-D-ribofuranosylamine – although prepared by

• synthetic sequence, the key reaction of which was a coupling of bisphosphonate 34 with isopropylidene-protected NR+ 29 under the Steglich esterification conditions in the presence of tri-n-octylamine, pyridine and DCC in DMF medium at 60 °C for 18 h (Scheme 19). Compound 36 was isolated in pure form by

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

• )-5 which after O-benzylation provided an inseparable 1:3 mixture of compounds 8a and 8b. A six-carbon chain was shortened by a diol formation–diol cleavage sequence followed by aldehyde oxidation and esterification to give 9a and 9b after chromatographic separation. They were transformed into (2S,3R

• removal of the chiral auxiliary with simultaneous formation of a N-Boc derivative 30. The hydroxymethyl to carboxylate transformation to form the protected diester (2S,3R)-31 required prior basic deacetylation followed by standard oxidation and esterification. Diastereoisomer (2S,3S)-31 was also prepared

• nitrogen was protected as N-Boc to furnish (4R,5R)-47. Under basic conditions the pyrrolidin-2-one ring was cleaved to provide a five-carbon chain of the target molecule. The final steps included esterification, desilylation and selective oxidation of the hydroxymethyl group followed by esterification

Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• ], electroreductive dehalogenation [7] and decarboxylation of diethyl 1,1-cyclopropyldicarboxylate [8]. Other methods include the transesterification of other alkyl cyclopropanecarboxylates [9] and the esterification with ethanol of the cyclopropanecarboxylic acid [10]. This product finds applications as lubricant

Selective ring-opening metathesis polymerization (ROMP) of cyclobutenes. Unsymmetrical ladderphane containing polycyclobutene and polynorbornene strands

• Yuan-Zhen Ke,
• Shou-Ling Huang,
• Guoqiao Lai and
• Tien-Yau Luh

Beilstein J. Org. Chem. 2019, 15, 44–51, doi:10.3762/bjoc.15.4

• linker is because the ester group could be selectively hydrolyzed in the presence of amides. This selectivity will be helpful for the structural elucidation of polymer 8. Thus, 10b was allowed to react with 11 to afford amide-alcohol 12 in 79% yield. Esterification of 12 with 13b furnished 70% yield of

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• sulfonated polymer-carbon nanotubes composites (CNT-P-SO3H) 100–102 were described as outstanding catalysts for liquid phase transesterification of triglycerides 103 with methanol. The catalysts were also used for the esterification of oleic acid (106) with methanol. The important feature of this study is

• temperature. The esterification of long chain-free fatty acids with methanol was performed well for 10–12 h (Scheme 20). To check the effect of acid groups, HMP-1 (113) was also used as a catalyst for the reaction and low yields of corresponding products were obtained [68]. In another study, a new microporous

• sulfonated by concentrated sulfuric acid or p-toluenesulfonic acid (Scheme 24) [73]. The catalytic applications of these sulfonated carbon catalysts were investigated in the esterification of oleic acid with methanol (with different ratios of MeOH/oleic acid) at 70 °C for 2 h. Theoretically, 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

• -phenanthroline) as the catalyst, 4a-Me was obtained in 86% yield after esterification. Other bidentate ligands such as bpy, phen, and dppe were not suitable for this reaction. Control experiments revealed that both the Co catalyst and the Mn reductant were indispensable to the reaction. The carboxylation of

• 14e containing a bicyclo[2.2.2]octane framework with ketone and dimethyl ketal moieties was also converted and the corresponding product was isolated as the methyl ester 15e-Me after esterification. For the Co-catalyzed C(sp3)–H carboxylation of allylarenes, a mechanism shown in Scheme 13 can be

A switchable [2]rotaxane with two active alkenyl groups

• Xiu-Li Zheng,
• Rong-Rong Tao,
• Rui-Rui Gu,
• Wen-Zhi Wang and
• Da-Hui Qu

Beilstein J. Org. Chem. 2018, 14, 2074–2081, doi:10.3762/bjoc.14.181

• and treated with NaBH4, protected by di-tert-butyl pyrocarbonate to get compound 3. The esterification reaction was carried out subsequently between hydroxy compound 3 and allylacetic acid to afford compound 4, which was further reacted with CF3COOH and followed by the anion exchange in the methyl

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• Artur Kasprzak Agnieszka Zuchowska Magdalena Poplawska Faculty of Chemistry, Warsaw University of Technology, Noakowskiego Str. 3, 00-664 Warsaw, Poland 10.3762/bjoc.14.177 Abstract Reactions applying amidation- or esterification-type processes and diazonium salts chemistry constitute the most

• commonly applied synthetic approaches for the modification of graphene-family materials. This work presents a critical assessment of the amidation and esterification methodologies reported in the recent literature, as well as a discussion of the reactions that apply diazonium salts. Common

• areas of research, including colloid chemistry and interface science; nevertheless, the basic rules of organic chemistry should be regarded as playing a leading role in covalent functionalization. Review Reactions of carboxyl groups: amidation, esterification A primary amine or a primary alcohol

Anomeric modification of carbohydrates using the Mitsunobu reaction

• Julia Hain,
• Patrick Rollin,
• Werner Klaffke and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1619–1636, doi:10.3762/bjoc.14.138

• achieve good results in the Mitsunobu procedure. We have reviewed on the one hand the literature on anomeric esterification, including glycosyl phosphates, and on the other hand glycoside synthesis, including S- and N-glycosides. The mechanistic details of the Mitsunobu reaction are discussed as well as

• , they can also be manipulated to one’s advantage, for example for the stereoselective formation of β-mannosides [28]. Reactions with protic acids to achieve anomeric esters The first application of the Mitsunobu reaction involved esterification of a secondary alcohol. Although an anomeric OH group

• -D-glucuronide products could be isolated in up to 50% yield. Similarly, regioselective esterification of unprotected allyl glucuronide 11 was performed by Juteau et al. with the acids 12–16 yielding anomeric mixtures of the respective 1-O-acyl-β-D-glucuronides 18–22 in quite acceptable yields even

Acyl-group specificity of AHL synthases involved in quorum-sensing in Roseobacter group bacteria

• Lisa Ziesche,
• Jan Rinkel,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2018, 14, 1309–1316, doi:10.3762/bjoc.14.112

• with cysteamine into the protected thiol 8 [39]. Steglich esterification [40] with different free acids led to nine saturated PCEs 10a–i, four monounsaturated acids (11a–d), 3-OH-C10:0-HSL PCE (12), and 2E,11Z-C18:2-PCE (13) after deprotection with acetic acid [41]. Although compounds 10–13 can be

Novel unit B cryptophycin analogues as payloads for targeted therapy

• Eduard Figueras,
• Adina Borbély,
• Mohamed Ismail,
• Marcel Frese and
• Norbert Sewald

Beilstein J. Org. Chem. 2018, 14, 1281–1286, doi:10.3762/bjoc.14.109

• and A succeeded as previously described in the literature; unit A (15) and C–D (16) were connected by Yamaguchi esterification to give 17 (Scheme 2) [45]. Then, Fmoc was cleaved from the N-terminus of unit C–D–A (17) using piperidine and the resulting crude amine was coupled to the corresponding

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

• with excellent enantioselectivity (Scheme 2d). Another class of chiral I(V) reagents 6 was synthesized by Wirth et al. who synthesized the desired compounds through esterification between chiral alcohols and the I(I)-substituted aromatic acids followed by oxidation with dimethyldioxirane (Scheme 2e

Recyclable hypervalent-iodine-mediated solid-phase peptide synthesis and cyclic peptide synthesis

• Dan Liu,
• Ya-Li Guo,
• Jin Qu and
• Chi Zhang

Beilstein J. Org. Chem. 2018, 14, 1112–1119, doi:10.3762/bjoc.14.97

• mediated by hypervalent iodine(III) reagents in recent years. In 2012, for the first time, we reported that the hypervalent iodine(III) reagent iodosodilactone (Figure 1) can serve as a condensing reagent to promote esterification, macrolactonization, amidation and peptide coupling reactions in the