The in situ generation and reactive quench of diazonium compounds in the synthesis of azo compounds in microreactors

• Faith M. Akwi and
• Paul Watts

Beilstein J. Org. Chem. 2016, 12, 1987–2004, doi:10.3762/bjoc.12.186

• amines. Nonetheless they highlight the green benefits that they offer. For example Noroozi-Pesyan et al. synthesized azo dyes by grinding derivatives of aniline with solid sodium nitrite in the presence of p-toluenesulfonic acid [3]. It was found that the yield of isolated azo dyes obtained increased

• concentrated 32% HCl and cooled. To this cooled solution, 3 mL of cold sodium nitrite solution (0.29 g in 5 mL of distilled water) was added drop wise until the potassium starch iodide paper test was positive. DMF (20 mL) was added to this, after which the solution was made up to a volume (100 mL) with

• hot concentrated 32% HCl (0.8 mL) and cooled. To this cooled solution, cold sodium nitrite solution (0.29 g in 5 mL of distilled water) was added drop wise until the potassium starch iodide paper test was positive. DMF (20 mL) was added to this after which the pH of the solution was buffered to afford

Synthesis of photoresponsive cholesterol-based azobenzene organogels: dependence on different spacer lengths

• Yuchun Ren,
• Bin Wang and
• Xiuqing Zhang

Beilstein J. Org. Chem. 2015, 11, 1089–1095, doi:10.3762/bjoc.11.122

• gel formation modes. Experimental Materials The starting materials, thylene glycol, 1,3-propanediol, 1,5-pentadiol, 1,6-hexanediol, 1,10-decanediol, 1,12-dodecanediol, cholesterol, 4-toluene sulfonyl chloride, phenol, 4-aminobenzoic acid, iodomethane, sodium nitrite, hydrochloric acid, sodium

Three-component synthesis of C₂F₅-substituted pyrazoles from C₂F₅CH₂NH₂·HCl, NaNO₂ and electron-deficient alkynes

• Pavel K. Mykhailiuk

Beilstein J. Org. Chem. 2015, 11, 16–24, doi:10.3762/bjoc.11.3

• approach to CF3-pyrazoles by a three-component reaction between electron-deficient alkynes, sodium nitrite and trifluoroethylamine hydrochloride was developed [46]. This method worked for both the mono- and disubstituted alkynes. Because of similar electronic properties of CF3 and C2F5 groups [1], it was

• suspension of C2F5CH2NH2·HCl (90 mg, 0.48 mmol, 3.0 equiv) in CH2Cl2 (4.0 mL)/water (0.2 mL), sodium nitrite (54 mg, 0.78 mmol, 5.0 equiv) and alkyne (0.16 mmol, 1.0 equiv) were added. The reaction mixture was vigorously stirred at 20 °C for 72 h. Water (1.0 mL) and CH2Cl2 (3 mL) were added. The organic

Derivatives of the triaminoguanidinium ion, 3. Multiple N-functionalization of the triaminoguanidinium ion with isocyanates and isothiocyanates

• Jan Szabo,
• Kerstin Karger,
• Nicolas Bucher and
• Gerhard Maas

Beilstein J. Org. Chem. 2014, 10, 2255–2262, doi:10.3762/bjoc.10.234

• 1,3-diketones follow condensation/cyclization pathways resulting in unsymmetrical N-heterocyclic products [14][15]. Azidation of TAG-Cl with two equivalents of sodium nitrite in water afforded the highly shock- and friction-sensitive (5-azido-1H-tetrazol-1-yl)carbonimidoyl diazide rather than the

Concise total synthesis of two marine natural nucleosides: trachycladines A and B

• Haixin Ding,
• Wei Li,
• Zhizhong Ruan,
• Ruchun Yang,
• Zhijie Mao,
• Qiang Xiao and
• Jun Wu

Beilstein J. Org. Chem. 2014, 10, 1681–1685, doi:10.3762/bjoc.10.176

• % yield. In the next transformation to trachycladine B the classic procedure with sodium nitrite in acetic acid proved to be inefficient as it gave complicated mixtures. Therefore, we applied an alternative method. In the past decades, adenosine deaminase (adenosine aminohydrolase, ADA, EC 3.5.4.4) and

Synthesis, characterization and DNA interaction studies of new triptycene derivatives

• Sourav Chakraborty,
• Snehasish Mondal,
• Rina Kumari,
• Sourav Bhowmick,
• Prolay Das and
• Neeladri Das

Beilstein J. Org. Chem. 2014, 10, 1290–1298, doi:10.3762/bjoc.10.130

• (TATs) 3 and 4, our strategy was to use the well established chemistry of conversion of aniline to the aryl diazonium ion and subsequent reaction with azide nucleophile. As shown in Scheme 1, treatment of the appropriate triaminotriptycene [36] with an aqueous solution of sodium nitrite in presence of

Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate

• James A. B. Laurenson,
• John A. Parkinson,
• Jonathan M. Percy,
• Giuseppe Rinaudo and
• Ricard Roig

Beilstein J. Org. Chem. 2013, 9, 2660–2668, doi:10.3762/bjoc.9.301

• displacement using sodium nitrite [39]. Cyclic sulfate 32b was exposed to sodium nitrite in DMF; the mixture was heated at reflux until completion of the reaction was confirmed by 19F NMR. Subsequent acid cleavage of the sulfate ester afforded the desired anti-diols in a disappointing yield (12% overall from

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

Flow synthesis of a versatile fructosamine mimic and quenching studies of a fructose transport probe

• Matthew B. Plutschack,
• D. Tyler McQuade,
• Giulio Valenti and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 2022–2027, doi:10.3762/bjoc.9.238

• nitrite in flow. While the use of supported reagents in flow is now well-established, the use of supported nitrite has not been widely adopted [20]. Amberlite IRA-900 was exchanged by eluting the chloride ion from the resin using a 1 M solution of sodium nitrite until no more chloride was observed via an

• increase concentration or use organic co-solvents further reduced the efficiency. Based on these problems, we turned our attention to Tiffeneau–Demjanov conditions using a catalytic amount of acid and sodium nitrite in water. Flow conditions enabled the use of high concentrations (1.0 M) and temperatures

The first example of the Fischer–Hepp type rearrangement in pyrimidines

• Inga Cikotiene,
• Mantas Jonusis and
• Virginija Jakubkiene

Beilstein J. Org. Chem. 2013, 9, 1819–1825, doi:10.3762/bjoc.9.212

• reaction of commercially or synthetically available 4,6-dichloropyrimidines with an excess of primary amines in boiling 2-propanol. As it is was shown by us earlier, the starting compounds 1 underwent smooth and high-yielding N-nitrosation reactions by using sodium nitrite in acetic acid at room

• temperature. However, the nitrosation of compound 1l, bearing a morpholino moiety in position 2 of the pyrimidine ring, was not selective. After the treatment of 1l with sodium nitrite in acetic acid at room temperature, a mixture of N- and C-nitrosated compounds 2l and 3 is formed (Scheme 3). This fact can

Ethyl diazoacetate synthesis in flow

• Mariëlle M. E. Delville,
• Jan C. M. van Hest and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2013, 9, 1813–1818, doi:10.3762/bjoc.9.211

• quantities. Ethyl diazoacetate was prepared in a biphasic mixture comprising an aqueous solution of glycine ethyl ester, sodium nitrite and dichloromethane. Optimization of the reaction was focused on decreasing the residence time with the smallest amount of sodium nitrite possible. With these boundary

• efficient than the sulfonylhydrazone pathway, we chose to synthesize EDA (1) from glycine ethyl ester (2) using readily available sodium nitrite [20] (Scheme 1). Although the diazotization step itself resembles the first step of Ley’s hydroxy acid synthesis, we specifically aimed to produce and isolate the

• ester (2) and sodium nitrite in a biphasic system of dichloromethane and an aqueous sodium acetate buffer. Dichloromethane was chosen as the organic phase to dissolve the water insoluble EDA, because of its low water uptake and low boiling point and its compatibility with potential follow-up reactions

Aerobic radical multifunctionalization of alkenes using tert-butyl nitrite and water

• Daisuke Hirose and
• Tsuyoshi Taniguchi

Beilstein J. Org. Chem. 2013, 9, 1713–1717, doi:10.3762/bjoc.9.196

• , and this observation has already been reported in previous radical oxynitration reactions of alkenes [22]. In addition, when alkene 1 was subjected to nitrous acid (HNO2), that was formed from sodium nitrite (NaNO2; 3 equiv) and acetic acid (3 equiv), and oxygen in water (30 equiv) and pentene (0.2 M

A bisazobenzene crosslinker that isomerizes with visible light

• Subhas Samanta,
• Harris I. Qureshi and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2012, 8, 2184–2190, doi:10.3762/bjoc.8.246

• bisazobenzene, 5,5'-((piperazine-1,4-diylbis(4,1-phenylene))bis(diazene-2,1-diyl))bis(2-acetamidobenzenesulfonic acid) (2): An ice-cold mixture of sodium 2-acetamido-5-aminobenzenesulfonate (4, 1.6 g, 6.3 mmol) and sodium nitrite (0.47 g, 6.8 mmol) in water (30 mL) was added dropwise to a mixture of

• -linked bisazobenzene derivative 2 was prepared by a double diazo-coupling reaction between the donor 1,4-diphenylpiperazine (7) and the acceptor 4-acetamido-3-sulfobenzenediazonium chloride (3), which was synthesized in situ by diazotization of sodium 2-acetamido-5-aminobenzenesulfonate (4) using sodium

• nitrite with HCl (Scheme 2). Compound 4 was prepared by hydrogenation with H2/Pd-C from sodium 2-acetamido-5-nitrobenzenesulfonate (5), which was obtained from commercially available sodium 2-amino-5-nitrobenzenesulfonate (6) by acetylation using acetic anhydride. 1,4-Diphenylpiperazine (7) was

Highly selective synthesis of (E)-alkenyl-(pentafluorosulfanyl)benzenes through Horner–Wadsworth–Emmons reaction

• George Iakobson and
• Petr Beier

Beilstein J. Org. Chem. 2012, 8, 1185–1190, doi:10.3762/bjoc.8.131

• conditions were tested, but no system for selective reduction of the nitro group was found. Diazotization was carried out with the aim to prepare 1,2-diarylethane 9d from aniline 8d (Scheme 3). A combination of sodium nitrite and phosphoric acid was used. (With HCl, substitution of the amino function by a

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

• Antonio Avellaneda,
• Courtney A. Hollis,
• Xin He and
• Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

• + H+] calcd for C36H43N12, 643.37282; found, 643.37632. 3,3’-Diiododiphenylmethane (5). Based on related procedures [21][32], 3,3’-diaminodiphenylmethane (0.62 g, 3.1 mmol) in concentrated sulfuric acid (10 mL) was stirred at 0 °C. Sodium nitrite (0.62 g, 9.0 mmol) in water (6 mL) was added dropwise

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• and sodium nitrite in water at 0–5 °C to provide an intermediate diazonium salt. The latter underwent cycloaddition with an isocyanate in a one-pot reaction to give compound 43 (Scheme 10) [41]. 5-Aminopyrazoles 45 have recently been prepared by Boc deprotection of the α-hydrazino acids 44 with TFA in

A surprising new route to 4-nitro-3-phenylisoxazole

• Henning Hopf,
• Aboul-fetouh E. Mourad and
• Peter G. Jones

Beilstein J. Org. Chem. 2010, 6, No. 68, doi:10.3762/bjoc.6.68

• , Technische Universität Braunschweig, Postfach 3329, D-38023 Braunschweig, Germany 10.3762/bjoc.6.68 Abstract A one-pot synthesis of 4-nitro-3-phenylisoxazole has been carried out by treatment of cinnamyl alcohol dissolved in acetic acid with sodium nitrite; in addition, 4-phenyl-3-furoxanmethanol was

• phenylfuroxans 2 and 3 [10]. According to the original report, 4-phenyl-3-furoxanmethanol (2) was obtained as the sole product in 40% yield, by treatment of cinnamyl alcohol (1) dissolved in acetic acid with concentrated aqueous sodium nitrite at 70 °C (Scheme 1). Results and Discussion Application of this

• 40–60 °C. The mass spectrum was taken on a Finnigan MAT 4515 spectrometer at 70 eV. Preparation of 4-phenyl-3-furoxanmethanol (2) and 4-nitro-3-phenylisoxazole (4): To a stirred solution of cinnamyl alcohol (1, 4.08 g, 30 mmol) in glacial acetic acid (6 mL), was added saturated aqueous sodium nitrite

Bis(oxazolines) based on glycopyranosides – steric, configurational and conformational influences on stereoselectivity

• Tobias Minuth and
• Mike M. K. Boysen

Beilstein J. Org. Chem. 2010, 6, No. 23, doi:10.3762/bjoc.6.23

• step however, on switching to L-selectride for the stereoselective reduction [26], the allosamine derived thioglycoside 10 was obtained in good overall yield. For an alternative route, 7 was transformed into the 3-O-triflate 9 and then subjected to nucleophilic displacement with sodium nitrite in the