Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• generate the reactive species by dehydration of carbamates under mild conditions and the ultimate formation of isocyanates which can be derivatized in situ [54]. The conditions were optimized with alcohol 25 substituted by a 2-phenylethyl group at the oxygen-bearing carbon atom (C4) and possessing gem

• -disubstitution at C3 on the three-membered ring. Alcohol 25 was readily converted to carbamate 26 by reaction with trichloroacetyl isocyanate followed by cleavage of the trichloroacetyl group by alkaline hydrolysis. Dehydration of carbamate 26 was achieved by treatment with trifluoroacetic anhydride in the

• of the substrate scope indicated that a broad range of alkyl chains, possibly incorporating heteroatoms, were compatible with the dehydration–[3,3]-sigmatropic sequence, as illustrated with the isolation of compounds 38–40 (72–79%) after nucleophilic trapping of the generated isocyanate intermediates

Synthesis of indole–cycloalkyl[b]pyridine hybrids via a four-component six-step tandem process

• Muthumani Muthu,
• Rakkappan Vishnu Priya,
• Abdulrahman I. Almansour,
• Raju Suresh Kumar and
• Raju Ranjith Kumar

Beilstein J. Org. Chem. 2018, 14, 2907–2915, doi:10.3762/bjoc.14.269

• cyclization with the carbonyl to give 11, which subsequently undergoes dehydration to yield the cyclododeca[b]pyridine-3-carbonitrile 12. The intermediate 12 upon oxidative aromatization by molecular oxygen as the sole oxidant yields the indole–cyclododeca[b]pyridine-3-carbonitrile 7f. This four-component

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

• triglycerides with methanol, the etherification of isopentene with methanol, the esterification of palm fatty acid distillate with methanol, the dehydration of D-xylose into furfural, the production of ethyl acetate from ethanol and acetic acid, and the transesterification of palm oil with methanol into biodiesel

• esterification under atmospheric conditions and conventional heating [75]. The catalyst showed excellent catalytic activity in the dehydration of D-xylose (139) into furfural (140) as an industrial platform molecule as well as the production of ethylacetate from ethanol and acetic acid [76]. The dehydration of D

Unprecedented nucleophile-promoted 1,7-S or Se shift reactions under Pummerer reaction conditions of 4-alkenyl-3-sulfinylmethylpyrroles

• Takashi Go,
• Akane Morimatsu,
• Hiroaki Wasada,
• Genzoh Tanabe,
• Osamu Muraoka,
• Yoshiharu Sawada and
• Mitsuhiro Yoshimatsu

Beilstein J. Org. Chem. 2018, 14, 2722–2729, doi:10.3762/bjoc.14.250

• products obtained were not the desired pyrrolo[3,2-c]azepines but were 2,6,7,8,9,10-hexahydro-4H-pyrrolo[3,4-g][1,5]oxazonines 25a–e, which were formed via a reaction route that involved the intramolecular dehydration of diols. To confirm the structure of 4H-pyrrolo[3,4-g]oxazines, we prepared an N

Impact of Pseudomonas aeruginosa quorum sensing signaling molecules on adhesion and inflammatory markers in endothelial cells

• Carmen Curutiu,
• Florin Iordache,
• Veronica Lazar,
• Aurelia Magdalena Pisoschi,
• Aneta Pop,
• Mariana Carmen Chifiriuc and
• Alina Maria Hoban

Beilstein J. Org. Chem. 2018, 14, 2580–2588, doi:10.3762/bjoc.14.235

• transmembrane conductance regulator (CFTR) gene [1]. This mutation determines alteration of ion transport and subsequent dehydration of the airway surface liquid, resulting in a viscous mucus layer on the airway surface of cystic fibrosis patients that deteriorate the mucociliary clearance and enhance the

A novel and practical asymmetric synthesis of eptazocine hydrobromide

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan,
• Kuaile Lin and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• reaction, a second strategy was proposed as illustrated in Scheme 4. Tetralone 4 was converted to dihydronaphthalene 11 by reduction with NaBH4 in methanol, followed by dehydration with POCl3/pyridine at reflux (85% yield). In order to get ketone 12, a series of oxidation conditions was tested (Table 2

• improved the reaction yield (Table 3, entries 4 and 5). The reductive methylation of 14 under Eschweiler–Clarke conditions (HCOOH/formalin/reflux) furnished 15 in quantitative yield. The latter was reduced by NaBH4 in methanol at room temperature, and then dehydration and hydrogenation with H2/Pd/C in

A general and atom-efficient continuous-flow approach to prepare amines, amides and imines via reactive N-chloramines

• Katherine E. Jolley,
• Michael R. Chapman and
• A. John Blacker

Beilstein J. Org. Chem. 2018, 14, 2220–2228, doi:10.3762/bjoc.14.196

• upon scale-up makes this a useful reaction to translate to flow. Likewise, imines are an important class of compounds and are increasingly used as precursors to optically active amines [35][36][37][38][39]. Whilst normally prepared via a corresponding carbonyl compound, final dehydration can be

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

• Scheme 7. The acid-catalyzed cleavage of the oxo-bridge of 34 gives benzylic carbocation 35. Consequently, after deprotonation and dehydration, chloro benzotropilium cation 37 undergoes hydrolysis to give 4,5-benzotropone (11) in aqueous reaction media. Using o-xylylene dibromide (38) as starting

• synthesis of Julia’s ketone was achieved by dehydration of the known keto-alcohol 164 by boric acid. Oxidation of Julia’s ketone with selenium dioxide gave 2,3-benzotropone (12). An alternative synthesis for 12, which represents a feasible route to avoid the disadvantage of selenium dioxide, is also

• synthesis of 7-hydroxy-2,3-benzotropone (241) was successfully realized by Dastan’s group (Scheme 47) [149]. Thiourea reduction of the peroxide linkage of 213 to the diol 282 and then simultaneously dehydration in situ gave the corresponding benzotropolone 241 in nearly quantitative yield. Recently, Arican

Recent advances in synthetic approaches for medicinal chemistry of C-nucleosides

• Kartik Temburnikar and
• Katherine L. Seley-Radtke

Beilstein J. Org. Chem. 2018, 14, 772–785, doi:10.3762/bjoc.14.65

• ribofuranose ring (which exists in equilibrium with the ring closed form), was exploited for C1' substitution using Grignard reagents [69]. Acid-catalyzed dehydration resulted in a diastereomeric mixture of C1'-disubstituted products 5 and 6 with an observed β/α ratio of 2:1 and 1:1, respectively. Similarily

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• the outcome of some reactions [29]. Non-spherical, high aspect ratio micelles are preferred for catalysis as such structures provide large surface area where reactions could take place [64]. This has been particularly the case for dehydration reactions [24]. Due to the combination of the structures

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

• Denisa Vargová,
• Rastislav Baran and
• Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

• , reduction, nitro-aldol reaction, and dehydration (Scheme 1). Methylation of the ester 2 in the alpha position proceeded easily with LDA as a base and methyl iodide as an alkylating agent. The ester functionality was then reduced with DIBAL in dichloromethane to afford aldehyde 4 in 90% yield. A base

Latest development in the synthesis of ursodeoxycholic acid (UDCA): a critical review

• Fabio Tonin and
• Isabel W. C. E. Arends

Beilstein J. Org. Chem. 2018, 14, 470–483, doi:10.3762/bjoc.14.33

• specifically acts on C12 (see postulated sequence of steps in Supporting Information File 1, Figure S2). The reaction sequence can be divided in 3 steps: firstly, the substrate is oxidized by a specific alcohol dehydrogenase and an ene-reductase-like enzyme. Then dehydration occurs, catalysed by a specific

Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ⁶-sulfanyl)acetic acid esters with aldehydes

• Anna-Lena Dreier,
• Andrej V. Matsnev,
• Joseph S. Thrasher and
• Günter Haufe

Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25

• on the initial formation of aldol addition products. These products could undergo acid catalyzed dehydration during aqueous work-up. Due to the presence of Lewis acids, which will be hydrolyzed, water would most probably eliminate via an intermediate benzyl cation, which would be stabilized by the

• conformer A, conformer B should be favored. Assisted by the chloride, this species is deprotonated forming the condensation product 4h with an (E)-configured double bond. Obviously, this formal dehydration is possible only in the presence of electron-donating para-substituents in the benzaldehyde. In order

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• , dehydration and aromatization reactions. The use of ionic liquids (non-volatile solvents) over toxic organic solvents makes it an environmentally benign process [45][46]. The synthesis of isomeric tetracyclic pyrazolo[3,4-b]pyridine-based coumarin chromophores 27 and 28 was reported by Chen et al. [47

• -trifluoromethylpyrazolo[1,5-a]pyrimidine derivative 124 by dehydration on refluxing with acetic anhydride (Scheme 34). All the synthesized compounds were screened for their anti-inflammatory activity. Mulakayala and co-workers [91] synthesized 7-trifluoromethylpyrazolo[1,5-a]pyrimidine carboxylates 127 by the reaction of

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

• : through dehydration in the case of 1 or radical reduction through the corresponding bisxanthate derivative in the case of 2. The required diol 3 could be obtained through a simultaneous hydrogenation of both, the cyclohexene and vinyl moieties of 1-aryl-4-vinyl-5,5,6,6-tetrafluorocyclohex-2-ene-1,4-diol 4

• steps less than the previous method. In addition, the present synthetic protocol involves several standard organic transformations, such as hydrogenation and dehydration, which are advantageous for a large-scale synthesis of the target compounds. Thus, we attempted a detailed examination of the short

Volatiles from the tropical ascomycete Daldinia clavata (Hypoxylaceae, Xylariales)

• Tao Wang,
• Kathrin I. Mohr,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 135–147, doi:10.3762/bjoc.14.9

• tetraketide, and if the dehydration step to install the C=C double bond in 10 would be omitted, this would lead to the hydroxy-ketone 11a for which a higher retention time than for 10 would be expected. The structure of such an alcohol was further supported by the fragment ion at m/z = 115 that may result

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

• sulfenylated dienes by dehydration. A series of aryl thiols with different steric and electronic properties give high yields of the thiol–yne products. Noteworthy is the high E-selectivity of the resulting alkene. Dependent on the substitution pattern of the aryl thiol a ratio up to 60:1 was observed due to

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• -dihydro-1H-isoindolin-1-ones via acid-catalyzed dehydration and subsequent nucleophilic substitution with the corresponding secondary amines. The procedure was successfully applied to the synthesis of known local anesthetics (AL-12, AL-12B and AL-5) in their neutral forms. Keywords: anesthetics

• retrosynthetic analysis is depicted in Scheme 1. The initial step comprises the photodecarboxylative addition of phenylacetate to commercially available N-(bromoalkyl)phthalimides, yielding the corresponding benzylated hydroxyphthalimidine derivatives as key intermediates. Subsequent acid-catalyzed dehydration

• structure of the dehydration product (E)-7a was furthermore confirmed by X-ray crystallographic analysis (Figure 3). Remarkably, the phenyl group of the arylmethylene unit is positioned almost perpendicular to the isoindolinone ring. Compound (E)-7a forms dimers through CH–π interactions between the phenyl

Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides

• Irwan Iskandar Roslan,
• Kian-Hong Ng,
• Gaik-Khuan Chuah and
• Stephan Jaenicke

Beilstein J. Org. Chem. 2017, 13, 2739–2750, doi:10.3762/bjoc.13.270

• -aminobenzothiazole (1a) via an Ortoleva–King type of reaction forms B [96][97]. This is followed by a nucleophilic addition and dehydration to form C. Upon deprotonation of the acidic proton at C by KOt-Bu, the desired product 3a is formed with release of KBr and tert-butanol. As proposed by Zeitler’s group, the

Solid-state studies and antioxidant properties of the γ-cyclodextrin·fisetin inclusion compound

• Joana M. Pais,
• Maria João Barroca,
• Maria Paula M. Marques,
• Filipe A. Almeida Paz and
• Susana S. Braga

Beilstein J. Org. Chem. 2017, 13, 2138–2145, doi:10.3762/bjoc.13.212

• their mass. This allows observing processes of dehydration, sublimation and decomposition [36]. The traces of γ-CD, fisetin, their 1:1 physical mixture and the γ-CD·fisetin inclusion compound are depicted in Figure 3. As can be seen from the TGA trace for fisetin no mass losses are observed between

• TG trace of the γ-CD·fisetin inclusion compound, that is, decomposition of the guest is not observed. The most striking difference between the trace of the inclusion compound and that of the physical mixture is observed in the dehydration profile. The mass loss from dehydration in γ-CD·fisetin is

Synthesis of substituted Z-styrenes by Hiyama-type coupling of oxasilacycloalkenes: application to the synthesis of a 1-benzoxocane

• James R. Vyvyan,
• Courtney A. Engles,
• Scott L. Bray,
• Erik D. Wold,
• Christopher L. Porter and
• Mikhail O. Konev

Beilstein J. Org. Chem. 2017, 13, 2122–2127, doi:10.3762/bjoc.13.209

• yield of the cyclic ether was still low (Table 2, entry 6). Microwave heating was not helpful (Table 2, entry 7). The non-nucleophilic base DBU was not effective in promoting the cyclization, either (Table 2, entry 8). We observed small amounts of products arising from the dehydration of 15 in the 1H

Iodoarene-catalyzed cyclizations of N-propargylamides and β-amidoketones: synthesis of 2-oxazolines

• Somaia Kamouka and
• Wesley J. Moran

Beilstein J. Org. Chem. 2017, 13, 1823–1827, doi:10.3762/bjoc.13.177

• -oxazolines, which are valuable heterocycles found in ligand scaffolds, natural products such as the leupyrrins [18][19], and potential pharmaceuticals (Figure 1) [20][21][22]. Traditional routes to this heterocycle include the dehydration of amino alcohols with carboxylic acids, however, this process

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

• presents a hydroxy and an aldehyde hydrate group. Yet obtaining this type of product is not an easy task because of its acid liability. Hydrolysis conditions must be mild to avoid dehydration leading to hydroxymethyl furaldehyde byproduct [22]. The crude agarose hydrolysate containing 2 was then directly

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• materials were obtained when the team used sucrose or starch as starting carbohydrate materials. In addition to microwave and acid reflux-mediated glucose dehydration reactions, the group of Wang developed an alternative protocol that combined glucose with monopotassium phosphate (KH2PO4) in a Teflon-lined

• ). In the absence of KH2PO4, irregular black carbon aggregates were obtained. Raman and TEM analysis showed both types of FCDs had graphitic crystallinity. This example highlights that an inorganic-based dehydrating agent could be used instead of a traditional diamine SPA to induce CD dehydration and

• improved materials with high QYs. Non-glucose monosaccharide-based fluorescent carbon dots In addition to glucose, different monosaccharides and polyols have also been utilised as carbon sources for the synthesis of FCD, although this approach is less common. The ability of glycerol to undergo dehydration

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• situ by the oxidative dehydrogenation of aldoximes in the presence of various oxidants [26][27][28][29], or by the dehydrohalogenation of hydroxyiminoyl halides promoted by organic or inorganic bases [30][31][32]. A less used synthetic procedure involves the oxidative dehydration of primary nitro