Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• reagents required the presence of 1,3-dimethyltetrahydropyrimidine-2(1H)-one (DMPU) (Scheme 21). Reactive alkylating reagents such as iodomethane, benzyl bromide, allyl iodide, propargyl bromide, or bromoacetate reacted well and afforded the products 80 in good yields. In an attempt to expand the available

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• substituted cyclohexanone 9, corresponding to the future C ring [24]. After deprotonation, the C3 position was stereoselectively alkylated using propargyl bromide, and the benzyl protecting group was cleaved with FeCl3, leading to spontaneous lactone closure. A Luche reduction stereoselectively converted

Cholyl 1,3,4-oxadiazole hybrid compounds: design, synthesis and antimicrobial assessment

• Anas J. Rasras,
• Mohamed El-Naggar,
• Nesreen A. Safwat and
• Raed A. Al-Qawasmeh

Beilstein J. Org. Chem. 2022, 18, 631–638, doi:10.3762/bjoc.18.63

• ]. Having oxadiazole-2-thiol 2 at hands, the reactive thiol was subjected to the reaction with propargyl bromide and sodium carbonate as a base to afford the thiopropargylated derivative 3 in 82% yield after 24 h (Scheme 2) [33]. Compound 3 was the starting point for a Mannich reaction to generate a library

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• propargyl bromide in the presence of K2CO3. The synthesis of compounds 54a–g started with β-ᴅ-lyxofuranosylthymine (51), which was first methoxytritylated at the C-5′ primary hydroxy position followed by mesylation of the C-3′ secondary hydroxy position. The subsequent treatment with sodium azide in DMF

• the nucleobases with propargyl bromide in the presence of K2CO3. Nucleoside 94 was synthesized from thymidine (93) which was first tritylated at the C-5′ primary hydroxy position followed by acetylation at the C-3′ secondary hydroxy group [61]. Next, detritylation and tosylation of the protected

Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

• Viola Kolaříková,
• Markéta Rybáčková,
• Martin Svoboda and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226

• -diyn-4-ol (4a). The compound was prepared according to a published procedure [32] by the reaction of ethyl formate with propargylmagnesium bromide, generated from propargyl bromide (5a), magnesium and a catalytic amount of HgCl2 to suppress the formation of allenylmagnesium bromide (Scheme 5). The

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• Discussion Synthesis of the host TBTQ-(OG)6. The sugar-functionalized host TBTQ-(OG)6 was synthesized starting from the known compound TBTQ-(OH)6 (Scheme 1) [31][32][33]. The reaction of TBTQ-(OH)6 with propargyl bromide in the presence of potassium carbonate gave the hexakis-propargyl ether, TBTQ-(OP)6, in

• imaging. Freeze drying was conducted on a Scientz-18N freeze dryer (Scientz Biotech, Zhejiang, China). Synthesis of TBTQ-(OP)6. A mixture of TBTQ-(OH)6 (2.17 g, 5.56 mmol), potassium carbonate (9.23 g, 66.8 mmol), and propargyl bromide (5.40 g, 44.5 mmol, 98 wt %) in acetonitrile (100 mL) was stirred and

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

• Ksenia I. Kaskevich,
• Anastasia A. Babushkina,
• Vladislav V. Gurzhiy,
• Dmitrij M. Egorov,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2020, 16, 1947–1954, doi:10.3762/bjoc.16.161

• between 2-thiouracil and propargyl bromide yielded 5H-thiazolo[3,2-a]pyrimidine-5-one (Scheme 5) [20][21][22][23][24]. Despite the wide variety of thiazolopyrimidines reported to date, phosphonylated analogues of compounds of this series are unknown. Of special interest is the design of molecules

• ]thiazol-2-yl)-2-(7-R-5-oxo-5H-thiazolo[3,2-a]pyrimidin-3-yl)acetonitriles. Synthesis of 3-acyl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-ones. Sonogashira coupling reaction of 6-amino-2-thiouracil with propargyl bromide. Reactions of 6-substituted 2-thiouracils 1a,b with chloroethynylphosphonates 2a–c

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• propargyl bromide (14f) to generate pyrroles 8i,j, respectively, in high yields. The synthesis of octahydropyrrolo[3,4-e]indoles 9/10 was achieved through a Diels–Alder reaction between the 2-vinylpyrroles 8a–j and 16a,b and maleimides 7a–c under thermal conditions (Scheme 3). N-Unsubstituted 2

Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation

• Sambasivarao Kotha,
• Gaddamedi Sreevani,
• Lilya U. Dzhemileva,
• Milyausha M. Yunusbaeva,
• Usein M. Dzhemilev and
• Vladimir A. D’yakonov

Beilstein J. Org. Chem. 2019, 15, 2774–2781, doi:10.3762/bjoc.15.269

• . In this regard, the required diyne precursor of thiazolidinedione was prepared from N-methylthiazolidine-2,4-dione (5a) and propargyl bromide (6a) in the presence of K2CO3 in DMF to afford the dipropargylated intermediate thiazolidinedione 7a in 85% yield. Diyne 7a was then reacted with propargyl

• generate new derivatives suitable for the multiple interaction sites. Further, the antitumour activity of these compounds were studied. Therefore, we synthesized the required diyne derivatives of thiazolidinedione for [2 + 2 + 2] cycloaddition, in the presence of propargyl bromide and K2CO3 in DMF. The

• bromide (6a) in the presence of Mo(CO)6 in acetonitrile at 90 °C under microwave irradiation (MWI) conditions to give the co-trimerized spiro derivative 8a (Scheme 2). The free NH moiety of thiazolidinedione 3 was alkylated using alkyl or aryl halides in the presence of Et3N using DCM as solvent. To our

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB₂-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

• Yang Bai,
• Cai-ping Liu,
• Di Chen,
• Long-hai Zhuo,
• Huai-tian Bu and
• Wei Tian

Beilstein J. Org. Chem. 2019, 15, 1925–1932, doi:10.3762/bjoc.15.188

• been successfully conducted. Subsequently, BM-Alk was synthesized by the alkylation reaction between benzimidazole and propargyl bromide according to the literature [46]. The appearance of the alkynyl absorption peaks at 2127 cm−1 in the FTIR spectrum (Figure S1A-a, Supporting Information File 1) and

Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks

• Clémence Moitessier,
• Ahmad Rifai,
• Pierre-Edouard Danjou,
• Isabelle Mallard and
• Francine Cazier-Dennin

Beilstein J. Org. Chem. 2019, 15, 721–726, doi:10.3762/bjoc.15.67

• through a reaction of furfuryl alcohol with propargyl bromide, as is referred in the study of Cao et al. (Scheme 1) [17]. As a matter of fact, a modification of the purification step was done in order to quantitatively enhance the yield. An alternative solvent-free microwave-assisted organic synthesis

• . Synthetic procedures 2-((Prop-2-ynyloxy)methyl)furan (2). Adapted from reference [17]: Furfuryl alcohol (9.0 mL, 103.8 mmol) was added dropwise to a solution of NaH (5.0 g, 207.5 mmol) in DMF (100 mL) at 0 °C. After 90 minutes, propargyl bromide (12.7 mL, 114.2 mmol) was added dropwise and the resulting

Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

• Antonella Di Vincenzo,
• Antonio Palumbo Piccionello,
• Alberto Spinella,
• Delia Chillura Martino,
• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• reacting the parent (5,11,17,23-tetra(tert-butyl))-(25,26,27,28-tetrahydroxy)calix[4]arene with an excess of propargyl bromide (see Scheme 1). The pH-dependent abilities of the relevant calixarene-based polymeric materials obtained were finally tested towards some suitable organic guests, suitably selected

Unnatural α-amino ethyl esters from diethyl malonate or ethyl β-bromo-α-hydroxyiminocarboxylate

• Eloi P. Coutant,
• Vincent Hervin,
• Glwadys Gagnot,
• Candice Ford,
• Racha Baatallah and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2853–2860, doi:10.3762/bjoc.14.264

• isoxazole-bearing α-amino esters 46a,b were also prepared via α-hydroxyimino esters. Their preparation started with the alkylation of diethyl malonate (4) with propargyl bromide to give compound 43 (which could not be separated from unreacted malonate and the bis-alkylated derivative). In the next step, [2

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• added and the reaction mixture was stirred. Then, propargyl bromide (2.30 g, 2.30 mmol) was added and the reaction mixture was heated at 80 °C for 24 h. The reaction mixture was cooled to room temperature and the precipitate was removed by filtration. After the filtration, the solvents were evaporated

Enantioselective phase-transfer catalyzed alkylation of 1-methyl-7-methoxy-2-tetralone: an effective route to dezocine

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

Beilstein J. Org. Chem. 2018, 14, 1421–1427, doi:10.3762/bjoc.14.119

• with allyl or propargyl bromide to obtain C12 and C13. In another way, cinchonidine was reduced by H2/Pd/C to yield dihydrocinchonidine, and then reacted with 4-trifluoromethylbenzyl bromide to obtained C14. C15 was prepared from cinchonidine via bromination, debromination and condensation with 4

An uracil-linked hydroxyflavone probe for the recognition of ATP

• Márton Bojtár,
• Péter Zoltán Janzsó-Berend,
• Dávid Mester,
• Dóra Hessz,
• Mihály Kállay,
• Miklós Kubinyi and
• István Bitter

Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63

• , 47.3 mmol, 1.2 equiv) and tetrabutylammonium bromide (2.54 g, 7.89 mmol, 0.2 equiv) were added and the mixture was cooled in an ice bath. Subsequently, propargyl bromide (80% in toluene, 4.83 mL, 43.3 mmol, 1.1 equiv) was added dropwise. The reaction mixture was stirred for 14 hours at ambient

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• in the second step using propargyl bromide in the presence of K2CO3, as a base, to afford exclusively the O-substituted quinoline, with no traces of the N-substituted analog. The formation of the O-propargyl regioisomer was confirmed by NMR spectroscopy using the connectivity between O-methylene and

Curcuminoid–BF₂ complexes: Synthesis, fluorescence and optimization of BF₂ group cleavage

• Henning Weiss,
• Jeannine Reichel,
• Helmar Görls,
• Kilian Rolf Anton Schneider,
• Mathias Micheel,
• Michael Pröhl,
• Michael Gottschaldt,
• Benjamin Dietzek and
• Wolfgang Weigand

Beilstein J. Org. Chem. 2017, 13, 2264–2272, doi:10.3762/bjoc.13.223

• release the curcuminoids as an alternative synthetic route to substituted curcumins. Results and Discussion Synthesis BF2 complexes First, we prepared the aldehydes 1a–h as the starting materials by Williamson ether synthesis of the corresponding hydroxybenzaldehydes with either propargyl bromide in dry

A postsynthetically 2’-“clickable” uridine with arabino configuration and its application for fluorescent labeling and imaging of DNA

• Heidi-Kristin Walter,
• Bettina Olshausen,
• Ute Schepers and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2017, 13, 127–137, doi:10.3762/bjoc.13.16

• ice bath. Then NaH (0.168 g, 4.20 mmol of 60% dispersion in mineral oil) was added and the reaction mixture was stirred for 15 min at 0 °C. The reaction mixture was warmed to room temperature and propargyl bromide (0.94 mL, 1.25 g, 8.40 mmol) was added slowly within 30 minutes. The reaction was

• at rt, 89%; b) 1. NaH, THF, 0 °C, 15 min, 2. propargyl bromide, rt, 18 h, 65%; c) TBAF, THF, rt, 5 min, 99%; d) DMTr-Cl, pyridine, rt, 5 h, 99%; e) 2-cyanoethyl-N,N-diisopropylchlorophosphoramidite, (iPr)2NEt, CH2Cl2, rt, 3 h, 95%; f) automated DNA synthesis; g) D1–D4, sodium ascorbate, TBTA, (CH3CN

A direct method for the N-tetraalkylation of azamacrocycles

• Andrew J. Counsell,
• Angus T. Jones,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2016, 12, 2457–2461, doi:10.3762/bjoc.12.239

• cyclen has been developed, using a partially miscible aqueous–organic solvent system with propargyl bromide, benzyl bromide, and related halides. The method works most effectively when the reaction mixture is shaken, not stirred. A crystal structure of the N-tetrapropargyl cyclam derivative 1,4,8,11

• tetrapropargyl cyclam derivative 3. Preparation of 3 was initially attempted via the direct alkylation of 1 (0.5 mmol) with excess propargyl bromide (6 equivalents) in acetonitrile and sodium carbonate, adapting the Trabaud protocol described above [35]. The desired compound was isolated in low yield (3%), with

• mmol scale. However, the synthesis of 3 was found to proceed smoothly when propargyl bromide and cyclam were combined in a mixture of aqueous sodium hydroxide and acetonitrile (Scheme 1). As noted above, a fine precipitate of 3 began to form at the phase interface within five minutes, and complete

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• bicycloisomerization reaction can be readily accessed in two steps. Alkylation of a secondary propargylamide can be achieved by sodium hydride deprotonation of its acidic proton and SN2 substitution of a substituted propargyl bromide (Scheme 5a). Alternatively, the same propargylamide can be alkylated under Mitsunobu

• conditions with a desired primary alcohol. One such alcohol, 2-cyclopropylprop-2-en-1-ol, can be synthesized using a modified Suzuki coupling procedure developed by Soderquist [49] (Scheme 5b). A cyclopropyl boronate can be generated from propargyl bromide, 9-BBN, and aqueous sodium hydroxide. This reactive

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• )propan-2-one (63) was easily generated via a two-step protocol (overall 63% yield) that started with the etherification of sodium para-methoxybenzyl alcolate with propargyl bromide [50]. The terminal alkyne on 62 was efficiently transformed into a ketone via an oxymercuration reaction using a combination

Exploring architectures displaying multimeric presentations of a trihydroxypiperidine iminosugar

• Camilla Matassini,
• Stefania Mirabella,
• Andrea Goti,
• Inmaculada Robina,
• Antonio J. Moreno-Vargas and
• Francesca Cardona

Beilstein J. Org. Chem. 2015, 11, 2631–2640, doi:10.3762/bjoc.11.282

• scaffold 5 (Scheme 3) was obtained by propargylation of pentaerythritol with propargyl bromide and NaH following a previously published procedure [35], while the dendrimeric nonavalent scaffold 6 (Scheme 3) was obtained in good yield from the reaction of tris[(propargyloxy)methyl]aminomethane with

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• : (a) Propargyl bromide, NaH, Et2O/DMF (quant. for both 26 and 30); (b) 3, CuSO4·5H2O, L-AsAc, THF/H2O (89% for 27 and 74% for 31); (c) H2, Pd/C 10%, MeOH. A: Ring A of the lactose moiety, B: Ring B of the lactose moiety. Reagents and conditions: (a) Bu2SnO, MeOH; propargyl bromide, TBAI, Tol (92%); (b

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• 134 was derived via bis-O-propargylation of compound 132 using propargyl bromide (126) under similar reaction conditions. Later, these compounds (133 and 134) were subjected to RRM and ERRM protocols under the influence of catalyst 1 in the presence of ethylene (24) to generate the tetracyclic systems