A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• . Subsequent reduction with sodium dithionite then afforded triamine 9. Another way comprised the installation of a nitroso group in compound 6 through reaction with in situ-generated nitrous acid giving nitroso compound 8. The subsequent reduction to the corresponding amine with hydrogen sulfide afforded the

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• -formyl amide products have unique properties and reactivity, but are difficult or impossible to access by traditional synthetic approaches. Keywords: formyl peptide; nitroaryl compound; nitroso compound; olefin cleavage; photocleavage; Findings The photochemistry of nitroaromatic functional groups has

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• isoxazolines 123 or cyclic nitrones 124 with an additional oxime group (Scheme 40) [130]. The authors showed that the initial product of the oxidative cyclization of oxime 122a under the action of TBN was the dimer 127 of the nitroso compound 126, which was formed, presumably, as a result of nitrosation of the

• C-centered radical 125 by TBN [130]. Intermediate 127 was isolated in 96% yield and its structure was confirmed by a single-crystal X-ray diffraction. Under the action of Et3N, the dimeric nitroso compound 127 was converted into the more stable oxime tautomeric form 123a (Scheme 41). Another

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• hydroxylamine and subsequently in situ oxidized to the nitroso compound using iron(III) chloride. After addition of acetic acid the reaction was allowed to proceed for several hours at room temperature to form the azo bond. For the benzyl alcohol-functionalized S-diazocine 5, the carboxylic acid of the

• zinc and the oxidation from the hydroxylamine to the nitroso compound. These reaction steps are difficult to monitor and furthermore the S-diazocine yield depends on the nature of substituents. However, the overall yields and the reliability of the formation of the azo group are superior to previously

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• and acetylacetone, providing adducts 5 in high to quantitative yields. Six-membered cyclic oxime 1a afforded the corresponding products only in moderate yields owing to the formation of undesired side products and polymerization of the α,β-unsaturated nitroso compound. This early example demonstrates

• the action of fluoride anion at −78 °C. It is worth paying attention that the malonate anion is generated prior the addition of TBAF, because of a high instability of the intermediate nitroso compound NSA2. Using this procedure, bicyclic oxime 13 was prepared in quantitative yield from precursor 12

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• -heteroarene reactants [91]. Nicholas and co-workers investigated the thermal (uncatalyzed) and Cu(I)-catalyzed reactions of 2-nitrosopyridine with various dienes [92]. Generally, the cycloaddition of an unsymmetrical diene and nitroso compound will lead to two regioisomers – proximal and distal (Scheme 11

• . General regioselectivity of the nitroso hetero-Diels–Alder reaction observed with unsymmetrical dienes. Effect of the nitroso species on the regioselectivity for weakly directing 2-substituted dienes. Regioselectivity of 1,4-disubstituted dienes 51. Nitroso hetero-Diels–Alder reaction between Boc-nitroso

• compound 54 and dienes 55. Nitroso hetero-Diels–Alder reaction between Wightman reagent 58 and dienes 59. Regioselective reaction of 3-dienyl-2-azetidinones 62 with nitrosobenzene (47). The regioselective reaction of 1,3-butadienes 65 with various nitroso heterodienophiles 66. Catalysis of the nitroso

Copper-catalyzed [3 + 2] cycloaddition of (phenylethynyl)di-p-tolylstibane with organic azides

• Mizuki Yamada,
• Mio Matsumura,
• Yuki Uchida,
• Masatoshi Kawahata,
• Yuki Murata,
• Naoki Kakusawa,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2016, 12, 1309–1313, doi:10.3762/bjoc.12.123

• 3a with NOBF4 afforded pentavalent organoantimony compound 6 in 85% yield. It is noteworthy that 5-bismuthanotriazole was demetallated upon reaction with NOBF4 to give the corresponding 5-nitroso compound [24]. Conclusion In conclusion, the Cu-catalyzed azide–alkyne cycloaddition of (phenylethynyl)di

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• the electrophilic component in a few reactions of NHC-bound aldehydes. The addition of acyl anions occur at the nitrogen atom of the nitroso compound. A NHC-catalysed cascade reaction of o-vinylarylaldehydes with nitrosoarenes afforded functionalised 2,3-benzoxazin-4-ones 45 [44]. The initial

meta-Oligoazobiphenyls – synthesis via site-selective Mills reaction and photochemical properties

• Raphael Reuter and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2012, 8, 877–883, doi:10.3762/bjoc.8.99

• in a good yield of 84%. However, pinacol was obtained as a side product and could not be separated by column chromatography. The impure diamine 12 was then subjected to the Mills reaction with one equiv of nitroso compound 10. The aim was to achieve selectively only one coupling at the less

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

• precursor 5, an addition product of HNO2 to the substrate 1 by a formal hetero Alder-ene reaction. Isoxazole 6 could then undergo electrophilic substitution via 7 to afford the nitroso compound 8, which in a final step would be oxidized to 4 under the reaction conditions. Previously reported approaches to 4