Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• required. Luo's team used Davis’ oxaziridine followed by treatment with K2CO3 to equilibrate the hydroxyketone, delivering an inseparable epimeric mixture (1:3) of 63 in 31% overall yield. An additional TBS protection allowed separation of the epimers. After acidic treatment, pure rhodomollein XX and 3-epi

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• derivatives were formed, which were reduced to amines in the second step (one pot) on a mercury cathode. The mercury cathode can be replaced by a carbon cathode, however, the yields are lower in this case [130]. Dioxirane and oxaziridine catalysis In dioxirane or oxaziridine catalysis, the nucleophilic attack

• presented in Scheme 31 [136]. An enantioselective oxidation can be achieved by combining a ketone catalyst with a chiral amine [137]. The resulting chiral oxaziridine intermediate promotes the hydroxylation of CH-acidic 1,3-dicarbonyl compounds in high yields and enantioselectivities (up to 99% ee) (Scheme

• oxidative coupling of primary amines and benzylic amines. General scheme of dioxirane and oxaziridine oxidative organocatalysis. Dioxirane organocatalyzed CH-hydroxylation involving aliphatic C(sp3)–H bonds. Enantioselective hydroxylation of CH-acids catalyzed by chiral oxaziridines. Iodoarene

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• with Davis’ oxaziridine and subsequent oxidation using Dess–Martin periodinane. Initial attempts for the key step (15 → 16) like a Nozaki–Hiyama–Kishi reaction failed, but lithium–halogen exchange using t-BuLi at low temperatures gave the desired vinyllithium intermediate I which successfully added to

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• cycloaddition adduct (not shown) [39] (Scheme 4B). Subsequent treatement with t-BuOLi resulted in the isomerization of the exo-olefin followed by exposure to n-butyllithium and Davis‘ oxaziridine 76 to give 77 in 60% yield with 89% ee. A three-step synthesis from 77 gave α,β-unsaturated amide 78, which

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• electrophilic hydroxylation at C4 When the lithium enolate of dimethyl N-Cbz-L-glutamate 63 was treated with Davis oxaziridine, an inseparable 9:1 mixture of diastereoisomers was formed with (2S,4S)-64 predominating (Scheme 16) [74]. For sodium and potassium enolates diastereoselectivity of the hydroxylation

• [86][87][88] or a Diels–Alder reaction using acylnitroso compounds [89]. However, when compared with these multistep approaches hydroxylation of pyroglutamic acid derivatives seems to be the simplest option. Treatment of the lithium enolate of benzyl N-Boc-pyroglutamate (S)-86 with Davis oxaziridine

• -glutamic acid [(2S,4S)-3] by electrophilic hydroxylation. Reagents and conditions: a) 3-phenyl-N-phenylsulfonyl oxaziridine, then LiHMDS, THF; b) 6 M HCl. Synthesis of all stereoisomers of 4-hydroxyglutamic acid (3). Reagents and conditions: a) Br2, PBr5, hν; b) MeOH, reflux; c) 6 M HCl, then pyridine

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• conditions (for selected other uses of oxaziridines in asymmetric α-hydroxylation reactions please see [123][124]). Interestingly, this transformation is accompanied by a kinetic resolution of the employed oxaziridine with s-factors up to 45 [116]. One potentially useful simple reagent to carry out oxygen

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

• M. Fernanda N. N. Carvalho,
• M. João Ferreira,
• Ana S. O. Knittel,
• Maria da Conceição Oliveira,
• João Costa Pessoa,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73

• =O double bond can be converted to ketals, thioketals or even dihalogenomethylenes [1] or react to form hydrazones [2]. On the other hand the C=N double bond can be converted into an oxaziridine group forming chiral oxaziridines which act as enantioselective oxidation reagents [1][3][4][5]. Other

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• leads to an intermediate α-aminoperoxy structure, which quickly collapses to the oxaziridine 71. Formation of C–X bonds α-functionalisation In two separate reports, Zhou and co-workers demonstrate the use of di-tert-butyl azodicarboxylate 72 (DBAD) in the direct amination of several different substrates

Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

• Brett N. Hemric and
• Qiu Wang

Beilstein J. Org. Chem. 2016, 12, 22–28, doi:10.3762/bjoc.12.4

• oxaziridine derivatives to create 1,3-oxazolidines, which were readily converted to the 1,2-oxyamino functionality (Scheme 1C) [14][15]. Recently, the Xu lab developed another iron-catalyzed intermolecular olefin-oxyamination reaction with O-alkylhydroxylamides to construct either 1,2-oxyamino or 2

Photoinduced 1,2,3,4-tetrahydropyridine ring conversions

• Baiba Turovska,
• Henning Lund,
• Viesturs Lūsis,
• Anna Lielpētere,
• Edvards Liepiņš,
• Sergejs Beljakovs,
• Inguna Goba and
• Jānis Stradiņš

Beilstein J. Org. Chem. 2015, 11, 2166–2170, doi:10.3762/bjoc.11.234

• from electrochemical and spectroscopic data. The outcome of the reaction depends on the light intensity and the concentration of O2. In the solid state the heterocyclic hydroperoxide is stable; in solution it is involved in further reactions. Keywords: heterocyclic hydroperoxide; oxaziridine

• group of 3 oxidizes it to oxaziridine intermediate 4 (Figure 4), which then undergoes a slow nucleophilic ring fission followed by cyclization (Scheme 3) to give 5 (Figure 4). The reaction depicted in Scheme 2 proceeds as long as the hydroperoxide 2 is present in the solution, and the crude product

• oxidizing capacity of the hydroperoxide when its concentration is less or comparable with the tetrahydropyridine leading to another versatile intermediate in organic synthesis – oxaziridine – as the inherent strain of the ring and the relatively weak N–O bond makes it unusually reactive. Electrochemical

A simple and efficient method for the preparation of 5-hydroxy-3-acyltetramic acids

• Johanna Trenner and
• Evgeny V. Prusov

Beilstein J. Org. Chem. 2015, 11, 323–327, doi:10.3762/bjoc.11.37

• in hands, we initially investigated the use of Davis oxaziridine chemistry (Table 1, entries 1 and 2) [11]. Deprotonation of 7 with an excess of LDA followed by treatment of the resulting bisenolate with camphoryl-based oxaziridine reagent 13 provided the desired product in 27% yield. Similar results

• were obtained when 3-phenyl-2-(phenylsulfonyl)oxaziridine (14) was employed, but product 15 from the concomitant reaction of bisenolate addition to N-sulfonimine byproduct was also isolated in 15% yield from this reaction. Some peroxide-based electrophilic oxidants (Table 1, entries 3–5) were also

An oxidative amidation and heterocyclization approach for the synthesis of β-carbolines and dihydroeudistomin Y

• Suresh Babu Meruva,
• Akula Raghunadh,
• Raghavendra Rao Kamaraju,
• U. K. Syam Kumar and
• P. K. Dubey

Beilstein J. Org. Chem. 2014, 10, 471–480, doi:10.3762/bjoc.10.45

• reaction with tryptamine in presence of NaI. The Schiff base on in situ oxidation with cumene hydroperoxide afforded an unstable oxaziridine derivative 15. Ring opening of the oxaziridine derivative 15 in presence of base afforded ketoiminol 16, which on iminol–amide tautomerism provided the required α

A practical synthesis of long-chain iso-fatty acids (iso-C₁₂–C₁₉) and related natural products

• Mark B. Richardson and
• Spencer J. Williams

Beilstein J. Org. Chem. 2013, 9, 1807–1812, doi:10.3762/bjoc.9.210

• sources [1] including the myxobacterium Stigmatella aurantiaca [21][65], and the oral bacterium Veillonella parvula [66], although the absolute configuration has not been reported. Diastereoselective hydroxylation [67] of the chelated Z-enolate derived from 28 using the Davis oxaziridine [68] afforded the

• -fatty acids 30 and 32, and (B) the ketone 33. Reagents and conditions: (a) Et3N, PivCl, LiCl, DMAP, (S)-4-benzyloxazolidinone, 71%; (b) NaHMDS, MeI, THF, 80%; (c) LiOH, H2O2, THF, H2O, 98%; (d) NaHMDS, Davis oxaziridine, THF, 71%; (e) i) iPrMgCl, MeOH, 76%, ii) NaOH, MeOH, 83%; (f) O2, PdCl2, DMA, H2O