Mechanochemical halogenation of unsymmetrically substituted azobenzenes

• Dajana Barišić,
• Mario Pajić,
• Ivan Halasz,
• Darko Babić and
• Manda Ćurić

Beilstein J. Org. Chem. 2022, 18, 680–687, doi:10.3762/bjoc.18.69

• -bromosuccinimide (NBS) under neat grinding (NG) and liquid-assisted grinding (LAG) conditions in a ball mill [51]. Insight into the dynamics of the formation of reaction intermediates and products was obtained by in situ Raman monitoring that provided information on the nature of the catalytically active PdII

• azobenzene with NXS and Pd(OAc)2 as precatalyst in the presence of TsOH and MeCN as solid and liquid additives, respectively, led to the ortho-halogenated products relative to the azo group of the azobenzenes. In situ Raman monitoring of these reactions confirmed that the most favorable reaction pathway is

• product L2Br-I in 96% yield after 15 hours of milling (Figure 2, Table 1, entry 5). The yield of this reaction was higher than the analogous reaction in MeCN solution (90% isolated yield under the mechanochemical conditions compared to 72% in MeCN solution) [52]. In situ Raman monitoring of the

Multi-faceted reactivity of N-fluorobenzenesulfonimide (NFSI) under mechanochemical conditions: fluorination, fluorodemethylation, sulfonylation, and amidation reactions

• José G. Hernández,
• Karen J. Ardila-Fierro,
• Dajana Barišić and
• Hervé Geneste

Beilstein J. Org. Chem. 2022, 18, 182–189, doi:10.3762/bjoc.18.20

• solution, the mechanochemical reactions were accomplished in the absence of solvents, in short reaction times, and in yields comparable to or higher than their solvent-based counterparts. Keywords: amidation; ball mill; fluorination; in situ monitoring; mechanochemistry; NFSI; Raman monitoring

• 2c''. Even though 1c and NFSI are solids (mp1c = 50–53; mpNFSI = 114–116 °C), rheological changes of the reaction mixture upon milling and formation of liquid 2c rendered a sticky reaction mixture, which affected the quality of the Raman monitoring (Figures S3 and S4 in Supporting Information File 1

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• acylation reagent with aluminium trichloride. In situ Raman monitoring of reaction of phthalic anhydride with p-xylene. FCR of pyrene and phthalic anhydride. Scope of acylation reagents in FCR under mechanochemical activation conditions and comparison with other reaction conditions (isolated yields

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

• spin resonance (ESR) spectroscopy; in situ Raman monitoring; mechanochemistry; quinoline; solid-state click chemistry; Introduction The copper-catalyzed azide–alkyne cycloaddition (CuAAC) represents a prime example of click chemistry. Click chemistry describes “a set of near-perfect” reactions [1] for

• difference in yields was significantly less pronounced. In situ Raman monitoring of mechanochemical click reactions In an attempt to gain a direct insight into reaction pathways of mechanochemical CuAAC reactions we repeated milling experiments 2a–2c in the preparation of the chloro-substituted product 5

• Raman monitoring of formation of the triazole 5 using copper(II) acetate monohydrate (5 mol %, method 2a) revealed strong luminescence of the reaction mixture indicating the direct involvement of the catalyst in the milling process and the formation of luminescent copper species, which hindered a

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• almost quantitative yields. The in situ Raman monitoring of a 1:2 mixture of 26 and 4-bromoaniline, which results in the formation of symmetrical bis(4-bromophenyl)thiourea 28d revealed thiocarbamoyl benzotriazole 27d as the reactive intermediate (Figure 4). Starting from 27a or 29, bis-thiourea 22a can

Raman spectroscopy as a tool for monitoring mesoscale continuous-flow organic synthesis: Equipment interface and assessment in four medicinally-relevant reactions

• Trevor A. Hamlin and
• Nicholas E. Leadbeater

Beilstein J. Org. Chem. 2013, 9, 1843–1852, doi:10.3762/bjoc.9.215

• Trevor A. Hamlin Nicholas E. Leadbeater Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269, USA 10.3762/bjoc.9.215 Abstract An apparatus is reported for real-time Raman monitoring of reactions performed using continuous-flow processing. Its capability

• over a temperature range from 25–120 °C. Seeing that the reaction did not reach completion within the 10 min in the heated zone, we then repeated the process at lower flow rates; first to 0.5 mL/min and then 0.25 mL/min. Our optimal conditions as determined by Raman monitoring were heating at 120 °C

• describe here an apparatus for real-time Raman monitoring of reactions performed using continuous-flow processing. We assess its capability by studying four reactions. We find that it is possible to monitor reactions and also, by means of a calibration curve, determine product conversion from Raman