(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

Continuous multistep synthesis of 2-(azidomethyl)oxazoles

• Thaís A. Rossa,
• Nícolas S. Suveges,
• Marcus M. Sá,
• David Cantillo and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2018, 14, 506–514, doi:10.3762/bjoc.14.36

• the incomplete conversions were ascribed to the presence of water in the reaction mixture. For this reason, further transformations were carried out in acetone dried over molecular sieves (3 Å). Using 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) as the base (Table 2, entry 5) full conversion of the azirine

• bromide added at 0 °C, cf. Table 2, entry 5) in dry acetone for 3 min. Then, DBN was added to neutralize the acidic medium, followed by a 2.5 M aqueous solution of NaN3 (1.1 equiv) and the resulting mixture was stirred at room temperature. A conversion of 89% to 7a from bromo oxazole 6a with a selectivity

• oxazole hydrobromide is required prior to the addition of NaN3 in order to avoid the generation of hydrazoic acid. Taking this into account, we decided to replace DBN by less expensive DIPEA for the subsequent reactions. Using both substrates 2a and 2b, it was observed that after 5 min of reaction at rt

p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• Madhuri Vangala Ganesh P Shinde Department of Chemistry, Indian Institute of Science Education and Research, Pune 411 008, India 10.3762/bjoc.12.197 Abstract The amidine bases DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene) display nucleophilic behaviour

• with a large substrate scope. Keywords: carbonates; DBN; DBU; lactams; p-nitrophenyl; Introduction Among various organic bases, amidines such as DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene) having an imino group attached to the α-carbon of the amine are

• synthetically useful and strong neutral bases. Besides, DBU and DBN catalyze various organic reactions such as dehydrohalogenations [1], carbonylations [2], amidations [3] and Baylis–Hillman reactions [4]. These bicyclic amidines have been thought to be non-nucleophilic bases, but meanwhile numerous examples

Efficient CO₂ capture by tertiary amine-functionalized ionic liquids through Li⁺-stabilized zwitterionic adduct formation

• Zhen-Zhen Yang and
• Liang-Nian He

Beilstein J. Org. Chem. 2014, 10, 1959–1966, doi:10.3762/bjoc.10.204

• , PEG150MeTMG and PEG150MeBu2N), all the O and N atoms coordinate with Li+ in a quasi-aza-crown ether fashion. OctIm, OctTMG, TMG, DBU and DBN generate complexes whereby Li+ is bound only to N atoms. In contrast, the coordination ability of the N atom in OctBu2N is not strong enough to form a homogeneous

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

• Guillaume Moreira,
• Laurence Charles,
• Mohamed Major,
• Florence Vacandio,
• Yohann Guillaneuf,
• Catherine Lefay and
• Didier Gigmes

Beilstein J. Org. Chem. 2013, 9, 1589–1600, doi:10.3762/bjoc.9.181

• di-tert-butyl nitroxide (DBN) as a control agent (Figure 1). The acetylation of VLA enabled the synthesis of well-defined glycopolymers with molar mass ranging from 2,000 to 40,000 g·mol−1 along with PDI values of about 1.1, whereas the NMP of VLA could not exceed Mn higher than 6,000, with PDI

• bath to quench the polymerization. For all of them, the monomer conversion was determined by 1H NMR analysis of the raw polymerization medium in DMSO-d6 solution, whereas the Mn and the PDI of the polystyrene chains were measured by SEC/THF. Structure of the SG1, TEMPO and DBN nitroxides and the

Reactions of nitroxides XIII: Synthesis of the Morita–Baylis–Hillman adducts bearing a nitroxyl moiety using 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl as a starting compound, and DABCO and quinuclidine as catalysts

• Jerzy Zakrzewski

Beilstein J. Org. Chem. 2012, 8, 1515–1522, doi:10.3762/bjoc.8.171

• bearing an EWG undergoes substitution. The reaction is carried out in the presence of either a tertiary amine (e.g., DABCO [2][3][4][5][6], quinuclidine and its derivatives [7][8][9][10][11][12], DBU [13][14], DBN [13], DMAP and its derivatives [4][15][16], urotropine [17], brucine N-oxide [18]) or a

Synthesis and photooxidation of styrene copolymer bearing camphorquinone pendant groups

• Branislav Husár,
• Norbert Moszner and
• Ivan Lukáč

Beilstein J. Org. Chem. 2012, 8, 337–343, doi:10.3762/bjoc.8.37

• afterwards to 6. All attempts to transform 9 directly to MCQ were unsuccessful. For example, such a transformation was tested by stirring compound 9 at ambient temperature with the following reagents: Methacrylic acid/Cs2CO3/DMF, methacrylic acid/DBN/benzene, methacrylic acid/NaH/n-hexane, methacrylic acid

Translation of microwave methodology to continuous flow for the efficient synthesis of diaryl ethers via a base-mediated S_NAr reaction

• Charlotte Wiles and
• Paul Watts

Beilstein J. Org. Chem. 2011, 7, 1360–1371, doi:10.3762/bjoc.7.160

• , tetramethylethylenediamine (TMEDA) and triethylamine affording negligible conversions of DCNB (4) to 2-chloro-1-(4-methoxyphenoxy)-4-nitrobenzene (7). In comparison, DBU (6), 1,5-diazabicyclo(4.3.0)non-5-ene (DBN) and 1,1,3,3-tetramethylguanidine (TMG) afforded 55.5, 56.3 and 55.1% conversions (at 1 equiv), respectively. If