1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• (viz 106) was formed. In part, this was found to be due to decomposition (and self-condensation reactions) of the dimethylthio-substituted allyl alcohol 105. However, also the minor adducts that were formed with the olefins were shown to be mixtures of exclusively non-cyclic allylation products of the

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• temperature control during the acetolysis step. The silylation method requires careful drying of 1 before the silylation but is otherwise experimentally simple. Hexol 6 was then DCB-protected using 2,4-dichlorobenzyl chloride and sodium hydride in DMSO. As self-condensation of the alkylating agent is possible

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• control over size and substitution pattern. Classical methods include chitinase-catalyzed assembly via ring-opening polyaddition of N,N’-diacetylchitobiose oxazoline derivatives [237][238][239] or self-condensation of N-phthalimide protected thioglycoside [240]. Enzymatic polymerization promoted by

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

• Zentralblatt summary. Additionally, ambiguities exist on the molecularity of the various reactions since Guareschi was often preparing β-aminocarbonyl derivatives in situ from the self-condensation of acetone and the aza-Michael trapping of mesityl oxide. This method works well only for acetone, while further

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• , difficulty in maintaining the reaction temperature and the occurrence of greater amounts of acetone and aldehyde self-condensation/polymerisation. By adopting a flow protocol and using a Comet X-01 micromixer (with linear scalability), more efficient mixing was attained and less aldehyde self-condensation

• of the reactor channels [123]. This article undoubtedly shows the capacity of flow systems in being easily telescoped for multistep syntheses. A self-condensation for the synthesis of 2-methylpentenal (86) was also developed by the group of Poliakoff (Scheme 17). The system exploits a sulfonic acid

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

• polypeptides, obtained the same compound, produced by an undesired concomitant self-condensation of the N-amidinopyrazole reagent. This transformation was further investigated in the preparation of N-amidino-amidinopyrazole hydrochloride from N-amidinopyrazole in DMF with DIPEA at room temperature in a

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• time on the self-condensation of ethyl cyanoacetate (4) in the presence of the optimized base system.a Michael addition–cyclocondensation synthesis of 1H-pyridine 5 or α-pyrone 6. Photophysical properties of 1H-pyridines 5. Photophysical properties of 1H-pyridines 5a and 5b in the solid state

Unexpected one-pot formation of the 1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene system from cyclopentanone, ammonia and dimethyl fumarate. Synthesis of highly strained polycyclic nitroxide and EPR study

• Sergey A. Dobrynin,
• Igor A. Kirilyuk,
• Yuri V. Gatilov,
• Andrey A. Kuzhelev,
• Olesya A. Krumkacheva,
• Matvey V. Fedin,
• Michael K. Bowman and
• Elena G. Bagryanskaya

Beilstein J. Org. Chem. 2019, 15, 2664–2670, doi:10.3762/bjoc.15.259

• ). The structure of the compound was finally confirmed by X-ray analysis and elemental analysis data (Figure 1). A possible mechanism for the formation of 1 is presented in Scheme 2. It is well-known that cyclopentanone is prone to self-condensation. In the presence of ammonia these reactions may lead to

A convenient and practical synthesis of β-diketones bearing linear perfluorinated alkyl groups and a 2-thienyl moiety

• Ilya V. Taydakov,
• Yuliya M. Kreshchenova and
• Ekaterina P. Dolotova

Beilstein J. Org. Chem. 2018, 14, 3106–3111, doi:10.3762/bjoc.14.290

• that mixing 2-acetylthiophene with a base in the absence of the ester (var. A) should be avoided due to notable darkening and self-condensation of the ketone, despite Prabhu’s recommendations [25]. Similar yields of a β-diketone were obtained if the ester of perfluorocarboxylic acid was first added to

• experiments are presented in Table 2. Preparation of aliphatic diketones by the same method is much more difficult due to self-condensation of esters. We tested the procedure suggested for the preparation of 1-(2-thienyl)butane-1,3-dione (5) by condensation of 2-acetylthiophene with ethyl acetate (Scheme 2

Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

• Aleksey A. Vasilev,
• Meglena I. Kandinska,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• David Sucunza,
• Juan J. Vaquero,
• Obis D. Castaño,
• Stanislav Baluschev and
• Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

• (Experimental part) with ethanol as the reaction medium. It is worth noting that replacement of the methanol with the environmentally more benign and less harmful ethanol significantly decreases the formation of blue-colored self-condensation byproducts (probably a chromophore constructed from quinolone and

• ), and efficient synthetic procedure. The method started with the quaternization of all starting materials (Scheme 3), which was performed in a sealed tube under an argon atmosphere to prevent possible side reactions like oxidation of the corresponding N-containing heterocylic intermediates or self

• -condensation of the resulting quaternary products. Carrying out the reaction in bulk without solvents allows scale-up of the quaternary salt synthesis and prevents possible environmental pollution. The known synthetic procedure [50][51] for the target dyes (Scheme 3) was modified to obtain the model compound

Novel approach to hydroxy-group-containing porous organic polymers from bisphenol A

• Tao Wang,
• Yan-Chao Zhao,
• Li-Min Zhang,
• Yi Cui,
• Chang-Shan Zhang and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 2131–2137, doi:10.3762/bjoc.13.211

• organic polymers (POPs) have been reported via Sonogashira–Hagihara coupling reaction [16], Suzuki–Miyaura chemistry [17], Yamato reaction [18], and self condensation of aromatic nitriles[19]. Although these methods can be used to construct POPs with high specific surface area values, these reactions are

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

• Mikael Bols and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12

• ]. They observed that though 41 was less reactive than the 2-O-benzyl derivative 42 it was nevertheless more reactive than the conventionally armed donor and could smoothly be coupled on the 4-OH group of the armed thioglycoside 43 without competing self-condensation of 43. The Yang group has also

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• of ketoketenes Using the chiral catalysts (S,Rp)-Josiphos F5 and F6, the Kerrigan group developed the asymmetric homodimerization of ketenes (Scheme 49) [92]. This self-condensation of ketoketenes proceeded in dichloromethane at –25 °C to give chiral β-lactones in high yields (up to 99%) with good to

• functionalized cyclopentenes in moderate yields with moderate to high enantioselectivities (Scheme 19) [50]. The presence of a trimethylsilyl group at the α-position of the allenone was key to achieving a regioselective [3 + 2] annulation. This remarkable steric effect probably suppressed the [4 + 2] self

• -condensation of the allenone [51]. 2.1.2 [3 + 2] Annulations using acyclic phosphines as chiral catalysts: In 2007, Wallace and co-workers employed the commercially available chiral phosphine (S,S)-DIOP F1 in asymmetric [3 + 2] annulations of allenic ketones with a diverse array of exocyclic enones, providing

An efficient method for the construction of polysubstituted 4-pyridones via self-condensation of β-keto amides mediated by P₂O₅ and catalyzed by zinc bromide

• Liquan Tan,
• Peng Zhou,
• Cui Chen and
• Weibing Liu

Beilstein J. Org. Chem. 2013, 9, 2681–2687, doi:10.3762/bjoc.9.304

• Liquan Tan Peng Zhou Cui Chen Weibing Liu School of Chemistry and Life Science, Guangdong University of Petrochemical Technology, 2 Guangdu Road, Maoming 525000, China 10.3762/bjoc.9.304 Abstract A self-condensation cyclization reaction mediated by phosphorus pentoxide (P2O5) and catalyzed by

• ; self-condensation; Introduction β-Keto amide and their derivatives are desired classes of intermediates for the synthesis of nitrogen- and oxygen-containing heterocyclic compounds since they possess six reactive sites in the same molecule (Scheme 1) [1][2][3][4][5][6][7]. A lot of reports can be found

• derivatives as the substrates prompted us to exploit the reactivity of the six different reactive positions of β-keto amides [14][15][16][17][18]. Two groups reported the self-condensation of N-aryl β-keto amides. The group of Zhang used Na2S2O8 as the reagent to induce this condensation [19] and the group of

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• ) [36]. Cheap and readily available malic acid (1.57) undergoes self-condensation to yield coumalic acid under strongly acidic dehydrating conditions [37][38][39][40]. The mechanism is believed to progress by initial dehydration/decarbonylation of malic acid to give an aldehyde acid enol 1.60 which then

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• subsequent introduction of additional SCF3 groups this system is not suitable due to effective self-condensation of thiocarbonyl difluoride (CF2=S) at higher concentrations. For this purpose the trimer of thiocarbonyl difluoride, bis(trifluoromethyl)trithiocarbonate (CF3S)2C=S, is more stable and reacts with

Hydroxyapatite supported caesium carbonate as a new recyclable solid base catalyst for the Knoevenagel condensation in water

• Monika Gupta,
• Rajive Gupta and
• Medha Anand

Beilstein J. Org. Chem. 2009, 5, No. 68, doi:10.3762/bjoc.5.68

• solvent-dependent [30][31]. In addition, the use of aqueous and highly protic solvents is currently of great importance since it avoids the problems of self-condensation, 1,2-elimination and retro-Knoevenagel condensation reactions. Herein, we report the facile preparation of hydroxyapatite supported