α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• cyclized radicals 22 couple subsequently with TEMPO providing lactams 12a–k after deprotection of the TMS groups. The cyclized tertiary alkoxyamines (R3 = Me) are known to be thermally labile [89][90][91][92] and consequently 4-isopropenylpyrrolidones 12g,k are isolated as the exclusive products. The

• . Diastereoselectivity for the formation of α-(aminoxy)amides 9i–k. Rationalization of the diastereoselectivity for the formation of the α-(aminoxy)amide 9l. Rationalization of the thermal radical cyclization diastereoselectivity of alkoxyamines 9a–k. (S)-Configuration at silyl ether function displayed as for 9i–k and

• 12i–k. The stereochemical course for the formation of products 12m,n by thermal radical cyclization of alkoxyamines 9m,n. Formation of bicycles 12o,p. Preparation of tertiary N-allylic α-(trimethylsilyl)amides 8a. Tandem nucleophilic ring opening/Brook rearrangement/radical oxygenationa. Hydroxyalkyl

Synthesis of 1-azaspiro[4.4]nonan-1-oxyls via intramolecular 1,3-dipolar cycloaddition

• Yulia V. Khoroshunova,
• Denis A. Morozov,
• Andrey I. Taratayko,
• Polina D. Gladkikh,
• Yuri I. Glazachev and
• Igor A. Kirilyuk

Beilstein J. Org. Chem. 2019, 15, 2036–2042, doi:10.3762/bjoc.15.200

• nitroxides, alkoxyamines 16a–c were prepared by Matyjaszhewski's method (Scheme 5) [20]. Oxidation of aminoacetate 10a along with the expected formation of nitroxyl radical 11a, gave another nitroxide, 17, in 22% yield. The IR spectra of 11a and 17 are very similar, showing the bands typical for ester group

• self-transformations. Oxidation of aminoalcohol 9a. The synthesis of alkoxyamines 16a–c. The alkoxyamine 18 synthesis. A possible mechanism of nitroxide 17 formation. Optimisation of the synthesis of nitroxide 1. Parameters of the EPR spectra (hyperfine coupling constants, aN; peak-to-peak linewidths

• , and microanalysis). Acknowledgements This work was supported by the Russian Foundation for Basic Research (grants No. 17-03-01132 [to Yu.V.K. & A.I.T., pyrroline-N-oxides and alkoxyamines] and 18-53-76003 within the framework of the ERA.Net RUS+ project ST2017-382: NanoHyperRadicals [to D.A.M

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• photochemical release of nitroxides should be achieved in the presence of O2. Thus, the triplet sensitized method may not be useful for physiological studies. The application of alkoxyamines as theranostic agents [37][38][39][40] has been proposed and reported by Brémond and co-workers [41][42]. Near-infrared

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• . Deprotonation of the latter with triethylamine in the presence of elemental sulfur allows the in situ generation of the corresponding imidazol-2-ylidene, which traps elemental sulfur yielding a 1,3-dihydro-2H-imidazole-2-thione as the final product. Keywords: alkoxyamines; imidazole N-oxides; imidazolium salts

• Scheme 1 occur smoothly with formaldimines 3 derived from aliphatic amines, but in the case of primary aromatic amines harsher reaction conditions are required [6]. To date, no synthesis of 1-alkoxyimidazole N-oxides derived from alkoxyamines (‘hydroxyamine ethers’) has been reported. An alternative

• , alkoxyamines are known not only as bioactive compounds [19][20] but also as important initiators of polymerization processes that have been extensively studied in the recent decade [21]. Among alkoxyamines, adamantyloxyamine (4) occupies a prominent position, and for that reason it was selected for experiments

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

• the presence of unprotected glucose and lithium salts (LiBr and LiCl) in DMF or DMA by electron spin resonance (ESR). NMP of styrene was then performed with two SG1-based alkoxyamines (BlocBuilder MA alkoxyamine (BB)) and a cellobiose-BB alkoxyamine (called cello-SG1) with or without lithium salts

Novel multi-responsive P2VP-block-PNIPAAm block copolymers via nitroxide-mediated radical polymerization

• Cathrin Corten,
• Katja Kretschmer and
• Dirk Kuckling

Beilstein J. Org. Chem. 2010, 6, 756–765, doi:10.3762/bjoc.6.89

• be ascribed to significant ionization biases during MALDI-TOF analysis leading to incorrect molecular weights. In addition, Dempwolf et al. [40] tested different alkoxyamines in different MALDI experiments. Supported by a comparison with other methods, they postulate a fragmentation mechanism inside