Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

• example, methyl acetoacetate (2a) possesses one CH-acidic methylene carbon which can be deprotonated in equilibrium by weak organic bases, such as triethylamine, piperidine or DBU, under thermodynamic conditions. Dimethyl acetone-1,3-dicarboxylate (3a) contains even two reactive methylene groups which can

(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene

• Nataliia V. Kirij,
• Andrey A. Filatov,
• Yurii L. Yagupolskii,
• Sheng Peng and
• Lee Sprague

Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40

• . The reaction mixture gave a complex mixture, in which (E)-butene 3a was identified as a major component. Product 3a was removed from bulk diglyme in vacuum and after subsequent distillation it was isolated with a yield of 23%. As the isolation of the 2-dehydrobromination products from organic bases

Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates

• Xing Liu,
• Wenjing Shi,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143

• nitrile of isatin 2a as standard reaction. The main experiments are briefly summarized in Table 1. At first, the reaction in DCM in the presence of common organic bases such as DMAP, DABCO, or DBU gave the expected spiro[indoline-3,5'-[1,2]diazepine] 3a in low to moderate yields (Table 1, entries 1–3

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

• Ksenia Malkova,
• Andrey Bubyrev,
• Stanislav Kalinin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 800–807, doi:10.3762/bjoc.19.60

• of the target compound 5a estimated by NMR (Table 1, entry 1). Different organic bases were tested, with piperidine performing most efficiently (Table 1, entry 4). Next it was found out that using o-azidobenzaldehyde (1a), PPh3, and an excess of piperidine in relation to ketosulfonamide 2a resulted

A trustworthy mechanochemical route to isocyanides

• Francesco Basoccu,
• Federico Cuccu,
• Federico Casti,
• Rita Mocci,
• Claudia Fattuoni and
• Andrea Porcheddu

Beilstein J. Org. Chem. 2022, 18, 732–737, doi:10.3762/bjoc.18.73

• organic bases like potassium tert-butoxide and imidazole proved to be as effective as triethylamine. Much to our surprise, we observed that the association between only 1 equivalent of triethylamine and 6 equivalents of sodium carbonate brought a good conversion rate of 1f in 2f at a frequency of 36 Hz

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

• Sayan Pramanik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 469–478, doi:10.3762/bjoc.18.49

• the structure of the product 3a. With 3-phenacylidene oxindole 1a and tosylhydrazine (2) as model substrates, we started the optimization of the reaction upon various parameters such as temperature, base and solvent. A variety of bases were examined in the reaction, both inorganic and organic bases

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• losses during extraction. No reaction was observed in CHCl3 (Table 1, entry 14) or utilizing organic bases (Et3N, DBU) (Table 1, entries 16–18). The efforts to increase the yield of diphenoxyketone 5a using 2 equivalents of phenol (2a) in the reaction with bromopropargylic alcohol 1a (Table 1, entries 8

Trichloroacetic acid fueled practical amine purifications

• Aleena Thomas,
• Baptiste Gasch,
• Enzo Olivieri and
• Adrien Quintard

Beilstein J. Org. Chem. 2022, 18, 225–231, doi:10.3762/bjoc.18.26

• there, simple decarboxylation, spontaneous or catalyzed through the addition of a small amount of low boiling organic bases, would liberate the volatile wastes and the clean pure amine. Herein, we present our success in developing such a technique. Results and Discussion In order to prove the

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

• Premansh Dudhe,
• Mena Asha Krishnan,
• Kratika Yadav,
• Diptendu Roy,
• Krishnan Venkatasubbaiah,
• Biswarup Pathak and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

• were formed that were still insufficient for complete characterization. Intending to improve the yield of 3aa, we screened various solvents, non-nucleophilic organic bases such as triethylamine and DBU, and several inorganic bases like K2CO3, Cs2CO3, and NaH (Table 1, entries 2–6). After systematic

• inert atmosphere prior to use. Organic bases, including DIPEA, Et3N, and DBU, were stored over anhydrous KOH pellets. In vitro cytotoxicity studies Cytotoxicity analysis in cancer and macrophage cells Cancer (MCF7, A431, A549, HEK293 or HeLa cell lines) or RAW264.7 cells were seeded in a 96-well plate

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• . Later, several groups performed the addition of N,N,N’,N’-tetramethylguanidine (TMG) to carbodiimides in order to produce the corresponding hexasubstituted biguanides (Scheme 39). These latter compounds found applications as strong organic bases [79], catalysts in transesterification reactions for the

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• reported by the previous literature shown in Scheme 1. As such, intrigued by this result and aiming to find selective methods to prepare both α-thio carbonyl compounds (3a and 4a), we decided to verify the influence of different inorganic and organic bases on the reaction (Table 1, entries 2–9). During

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• replacement of pyridine by other organic bases/ligands (4-DMAP, 2,2’-bipy, Et3N, TMEDA, 8-hydroxyquinoline) resulted in poorer yields of the target product in all cases (Table 1, entries 6–10). The use of copper(II) fluoride (in contrast to triflate) instead of acetate had practically no effect on the

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• reaction (see Table 1). Initially, the catalytic ability of organic bases was studied for the Henry/acetalyzation reaction by using 0.1–1.0 equiv of catalyst in THF as a solvent. Unfortunately, no product formation was observed in the presence of N,N-dimethylaniline (Table 1, entry 1) and unidentified

NHC-catalyzed enantioselective synthesis of β-trifluoromethyl-β-hydroxyamides

• Alyn T. Davies,
• Mark D. Greenhalgh,
• Alexandra M. Z. Slawin and
• Andrew D. Smith

Beilstein J. Org. Chem. 2020, 16, 1572–1578, doi:10.3762/bjoc.16.129

• observed, which served as a basis for further optimization. Variation of the base showed caesium carbonate to be significantly more effective than the organic bases examined, giving 88% conversion to product 6 (Table 1, entries 2 and 3). Trialling a number of alternative solvents, including dichloromethane

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

• Péter Bagi,
• Réka Herbay,
• Nikolett Péczka,
• Zoltán Mucsi,
• István Timári and
• György Keglevich

Beilstein J. Org. Chem. 2020, 16, 818–832, doi:10.3762/bjoc.16.75

• , such as trimethylamine, N,N-diisopropylethylamine, pyridine, 4-dimethylaminopyridine, n-butyllithium, NaH and Cs2CO3 were tested. The initial experiments showed that practically no isomerization occurred when phenyl-3-phospholene oxide 1a was refluxed in toluene in the presence of organic bases (see

Microwave-assisted efficient and facile synthesis of tetramic acid derivatives via a one-pot post-Ugi cascade reaction

• Yong Li,
• Zheng Huang,
• Jia Xu,
• Yong Ding,
• Dian-Yong Tang,
• Jie Lei,
• Hong-yu Li,
• Zhong-Zhu Chen and
• Zhi-Gang Xu

Beilstein J. Org. Chem. 2020, 16, 663–669, doi:10.3762/bjoc.16.63

• investigated the effect of different inorganic and organic bases (Table 1). It was interesting to note that all of the bases tested in the study afforded the desired enol tetramic acid derivative 7a after the reaction was heated under the microwave irradiation conditions. The ketone compound 6a could be the

• intermediate which would be quickly converted into the more stable enol product 7a. When the inorganic bases, such as Cs2CO3, NaOH, and Na2CO3, were tested, the desired product 7a was obtained in 56–72% yields (Table 1, entries 1–3). In contrast, the organic bases TEA and DMAP (Table 1, entries 4, 5, 7, 8

Design and synthesis of diazine-based panobinostat analogues for HDAC8 inhibition

• Sivaraman Balasubramaniam,
• Sajith Vijayan,
• Liam V. Goldman,
• Xavier A. May,
• Kyra Dodson,
• Sweta Adhikari,
• Fatima Rivas,
• Davita L. Watkins and
• Shana V. Stoddard

Beilstein J. Org. Chem. 2020, 16, 628–637, doi:10.3762/bjoc.16.59

• (PPh3)2 and Na2HPO4 as the base in a dioxane/water system under heating conditions of 90 °C. To improve the overall chemical yields, we evaluated several organic bases and found that TEA (4.0 equiv) improved the yield to 55%. This success was attributed to the improved increased solubility of TEA in the

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

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• opimization of various bases, we found that K2CO3 owned a slimilar reactivity as Cs2CO3, while CsOAc with weaker alkalinity showed a lower activity than K2CO3, giving a yield of 62% (Table 1, entries 8 and 9). Besides, organic bases such as Et3N and N,N-diisopropylethylamine (DIPEA) were not effective for

One-pot synthesis of epoxides from benzyl alcohols and aldehydes

• Edwin Alfonzo,
• Jesse W. L. Mendoza and
• Aaron B. Beeler

Beilstein J. Org. Chem. 2018, 14, 2308–2312, doi:10.3762/bjoc.14.205

• its original disclosure, particular in the area of asymmetric synthesis [22][23][24]. Other notable advancements include the expansion of its scope by using organic bases and a one-pot oxidation/epoxidation sequence of benzyl alcohols with manganese dioxide and an exogenous sulfonium salt [25][26

Mechanochemistry of nucleosides, nucleotides and related materials

• Olga Eguaogie,
• Joseph S. Vyle,
• Patrick F. Conlon,
• Manuela A. Gîlea and
• Yipei Liang

Beilstein J. Org. Chem. 2018, 14, 955–970, doi:10.3762/bjoc.14.81

• -, monomethoxytrityl- or dimethoxytrityl chloride (Scheme 1) [39]. A variety of temperatures and either inorganic or low-melting organic bases were surveyed. Optimal yields were achieved at 140 °C using DABCO by hand-grinding the reaction mixture in molten tetra-n-butylammonium bromide (TBAB) for five minutes. In the

Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

High-yielding continuous-flow synthesis of antimalarial drug hydroxychloroquine

• Eric Yu,
• Hari P. R. Mangunuru,
• Nakul S. Telang,
• Caleb J. Kong,
• Jenson Verghese,
• Stanley E. Gilliland III,
• Saeed Ahmad,
• Raymond N. Dominey and
• B. Frank Gupton

Beilstein J. Org. Chem. 2018, 14, 583–592, doi:10.3762/bjoc.14.45

• with organic bases (Table 4, entries 5 and 6) resulted in only moderate conversions to the desired product; however, using a 1:1 mixture of K2CO3/Et3N (1:1) resulted in 88% conversion (Table 4, entry 6) to 1, with corresponds to an isolated yield of 78%. Conclusion In summary, we have developed a high

Mechanochemical N-alkylation of imides

• Anamarija Briš,
• Mateja Đud and
• Davor Margetić

Beilstein J. Org. Chem. 2017, 13, 1745–1752, doi:10.3762/bjoc.13.169

• molar ratios of reagents. When 0.3 equivalents of dibromide 2 were used, bisalkylation was the sole reaction and imide 4 was isolated in 52% yield (Table 1, entry 5). Other inorganic and organic bases employed were less reactive than K2CO3, whereas Cs2CO3 showed a higher reactivity, which, due to the

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• our previous researches [4][51], it is found that the bases used have a significant influence on the yields of the reaction. Thus, several bases such as NaOH, KOH, Cs2CO3, K2CO3, t-BuOK, Et3N and DBU were investigated and the results are shown in Table 1. It is notable that both inorganic and organic

• bases could facilitate the reaction successfully. K2CO3 exhibited the best yield of 72% (Table 1, entries 1–7) as compared with other bases for the reaction. In further tests, different loadings of Pd/MgAl-LDHs were employed in the model reaction (Table 1, entries 8–10) in order to optimize the usage of