The LANCA three-component reaction to highly substituted β-ketoenamides – versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

• Tilman Lechel,
• Roopender Kumar,
• Mrinal K. Bera,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2019, 15, 655–678, doi:10.3762/bjoc.15.61

• . The easily introduced C-2 alkenyl groups may also be oxidized. Thus, dihydroxylation of the vinyl group in PM7 followed by oxidative cleavage afforded pyrimidine derivative PM50 having a formyl group at C-2 (Scheme 12) [31]. Next, the conversion of the 5-alkoxy groups of the pyrimidine derivatives PM

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• . The reduction of ester 76 with LiAlH4 and oxidative cleavage of the resulting 1,2-diol with NaIO4 delivered the highly substituted gem-difluorocyclopropanecarboxaldehyde 77 (72%) possessing a quaternary stereocenter (Scheme 26) [65]. Other examples of post-functionalization involve iodolactonization

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

• equimolar amounts of easily separable cycloadducts 75 and 76 (Scheme 19) [81]. The bicyclic framework in the latter compound was first reduced and the hydroxy group was protected as acetate. Then the oxidative cleavage of the C=C bond gave diacid 77 (readily purified as dimethyl ester 78) which is a

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• glycols, epoxides, and olefins takes place by the action of hypervalent iodine [38][71][72]. For example, Havare and Plattner reported the oxidative cleavage of α-aryl aldehydes using iodosylbenzene to give chain-shortened carbonyl compounds and formaldehyde [71]. In the field of carbohydrate chemistry

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols

• Katrina Tait,
• Alysia Horvath,
• Nicolas Blanchard and
• William Tam

Beilstein J. Org. Chem. 2017, 13, 2888–2894, doi:10.3762/bjoc.13.281

• includes the reduction to form alkane 8 [3], oxidative cleavage of the C=C bond to form 9 [4], ring-opening metathesis to form functionalized alkenes 10 and 11 [4], dihydroxylation to form diol 12 [5], ruthenium-catalyzed [2 + 2] cycloaddition with unsymmetrical alkynes to form regioisomers 13 and 14 [6

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Synthesis of D-manno-heptulose via a cascade aldol/hemiketalization reaction

• Yan Chen,
• Xiaoman Wang,
• Junchang Wang and
• You Yang

Beilstein J. Org. Chem. 2017, 13, 795–799, doi:10.3762/bjoc.13.79

• spectra of 8 (see Supporting Information File 1 for details). Cleavage of the isopropylidene acetal group in 8 under acidic conditions gave diol 9 (50%). However, oxidative cleavage of diol 9 with sodium periodate resulted in the unexpected formation of α,β-unsaturated aldehyde 10 in 71% yield, indicating

• isopropylidene acetal group in 7 was cleaved under acidic conditions to produce triol 11 in 86% yield (Scheme 3). Cleavage of the resulting vicinal diol in 11 with sodium periodate led to the C4 aldehyde 3 in nearly 60–70% yield. In this oxidative cleavage reaction, almost no elimination product was found based

• , Scheme 4). In addition, a trace amount of the deacetylated product was also detected . DDQ-mediated oxidative cleavage of the PMB group in alcohol 14 produced only a moderate yield (≈50%) of the 5,7-diol probably due to the presence of the free 7-hydroxy group. We envisaged that protection of the free 7

Unusual reactions of diazocarbonyl compounds with α,β-unsaturated δ-amino esters: Rh(II)-catalyzed Wolff rearrangement and oxidative cleavage of N–H-insertion products

• Valerij A. Nikolaev,
• Jury J. Medvedev,
• Olesia S. Galkina,
• Ksenia V. Azarova and
• Christoph Schneider

Beilstein J. Org. Chem. 2016, 12, 1904–1910, doi:10.3762/bjoc.12.180

• .12.180 Abstract Rh(II)-сatalyzed reactions of aroyldiazomethanes, diazoketoesters and diazodiketones with α,β-unsaturated δ-aminoesters, in contrast to reactions of diazomalonates and other diazoesters, give rise to the Wolff rearrangement and/or oxidative cleavage of the initially formed N–H-insertion

• other reaction processes were observed – the Wolff rearrangement and the assumed oxidative cleavage of the initial reaction products. Several examples of Rh-catalyzed reactions of diazocarbonyl compounds with N–H-substrates, which are accompanied by the Wolff rearrangement with formation of

• aroyldiazomethanes 2a–c and dibenzoyldiazomethane 3c with relatively high to almost quantitative yields (50–99%). It can be suggested that the appearance of amides 4 and 7 in these catalytic processes is a result of an oxidative cleavage of some reaction products, which were initially formed during the interaction

Synthesis of the C8’-epimeric thymine pyranosyl amino acid core of amipurimycin

• Pramod R. Markad,
• Navanath Kumbhar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2016, 12, 1765–1771, doi:10.3762/bjoc.12.165

• oxidative cleavage of diol with silica-supported NaIO4 gave aldehyde that was directly reacted with ethyl 2-(triphenylphosphoranylidene)acetate to give α,β-unsaturated ester 6 (E/Z = 92:8) in 83% yield over three steps. Reduction of ester 6 (E-isomer) with DIBAL-H gave allyl alcohol 7 – a synthone for the

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• of aldehydes and ketones 80 by hydrogen peroxide in ionic liquid [TEBSA][BF4] resulted in carboxylic acids and esters 81 in good to high yields (Scheme 26) [256]. Oxidation with H2O2–base systems: The oxidative cleavage of ketones 82 with hydrogen peroxide in alkaline solution yielded carboxylic

Synthesis of a deuterated probe for the confocal Raman microscopy imaging of squalenoyl nanomedicines

• Eric Buchy,
• Branko Vukosavljevic,
• Maike Windbergs,
• Dunja Sobot,
• Camille Dejean,
• Simona Mura,
• Patrick Couvreur and
• Didier Desmaële

Beilstein J. Org. Chem. 2016, 12, 1127–1135, doi:10.3762/bjoc.12.109

• from the monoproduct, potassium carbonate treatment gave the expected diepoxide 7. Oxidative cleavage with periodic acid provided the corresponding dialdehyde 5 in 17% overall yield from squalene. The perdeuterated phosphonium salt 9 was obtained by simple condensation of commercially available 2

• 19 in 96% yield which was further elaborated into aldehyde 20 in 16% overall yield according to the three-step van Tamelen sequence (i. NBS, THF, H2O; ii. K2CO3, MeOH; iii. H3IO6, Et2O) [30]. Interestingly enough, the 1,3-dioxane group survived the strongly acidic conditions of the oxidative cleavage

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• -methoxybenzyloxy)-3-methylbut-2-enyl nitrate (68% yield) as stable, colourless oils. Mild oxidative cleavage of the PMB groups using DDQ in wet DCM generated the desired 1° allylic alcohol (E)-3-methyl-4-hydroxybut-2-enyl nitrate ((E)-11) and (Z)-3-methyl-4-hydroxybut-2-enyl nitrate ((Z)-12) in 62% and 53% yields

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• efficient platforms for bidentate coordination in metal catalysis and good precursors of carboxylic acids, ketones and aldehydes upon oxidative cleavage of the keto/diol moiety [72]. More recently, a comprehensive study on the first evidence of the utility of these acceptors in organocatalysis has been

Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents

• Daniel Wiegmann,
• Stefan Koppermann,
• Marius Wirth,
• Giuliana Niro,
• Kristin Leyerer and
• Christian Ducho

Beilstein J. Org. Chem. 2016, 12, 769–795, doi:10.3762/bjoc.12.77

• followed by an azide reduction, Boc protection, saponification of the ester, peptide coupling with the amino acid 17, oxidative cleavage of the double bond to give 18 and an intramolecular reductive amination in order to construct the seven-membered ring. Methylation with subsequent acidic global

Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

• Thibault E. Schmid,
• Sammy Drissi-Amraoui,
• Christophe Crévisy,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 2418–2434, doi:10.3762/bjoc.11.263

• transformations of the γ,δ-unsaturated 1,4-adducts were successfully performed: an oxidative cleavage afforded for example ketoester 52 (Scheme 15). Moreover, the in situ trapping of the addition product with acetic anhydride led to the regeneration of the lithium enolate, which was allylated and submitted to

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• 70% overall yield. The synthesis started with 4-bromo-1,10-phenanthroline subjected to an oxidative cleavage with potassium permanganate to afford binicotinic acid. The binicotinic acid product was esterified using dicyclohexylcarbodiimide (DCC) in methanol and the resulting ester was cross-coupled

• ) has been performed by Lotter and Bracher [67]. The route included four steps, but unfortunately, the overall yield was only 7%. Like in method A, the synthesis started with 1,10-phenanthroline to prepare binicotinic acid via oxidative cleavage by potassium permanganate. The esterification took place

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• heterocycles (16 and 15 respectively), the latter reported here for the first time. The products arising from oxidative cleavage, the N-allylisatins, are diminished under these optimised conditions, and appear to arise only after longer reaction times. The proposed mechanism for the formation of spiro

• 1,3-rearrangement process. The N-allylisatins observed [4] are likely to be formed by oxidative cleavage processes as previously reported [4][11]. Control of the branch points in the overall base-catalysed cascade allylation reactions with indigo is clearly important in achieving practical synthetic

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

• attempts to remove the benzyl group under various catalytic hydrogenation conditions failed entirely. Cleavage of the DMB group with TFA [16] was also tried, but brought no success and extensive formation of polymerization products of the corresponding iminium ion was observed. Oxidative cleavage of the

Synthesis of the furo[2,3-b]chromene ring system of hyperaspindols A and B

• Danielle L. Paterson and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 265–270, doi:10.3762/bjoc.11.29

• product 19. Dihydroxylation of 19, followed by oxidative cleavage of the resultant diol gave aldehyde 20 in 80% yield over two steps. Addition of lithiate 16 to aldehyde 20 gave alcohol 21 in 87% yield as an inseparable 1:1 mixture of diastereoisomers. Hydrogenolysis of the benzyl ether in 21 gave ketal

Enantioselective synthesis of polyhydroxyindolizidinone and quinolizidinone derivatives from a common precursor

• Nemai Saha and
• Shital K. Chattopadhyay

Beilstein J. Org. Chem. 2014, 10, 3104–3110, doi:10.3762/bjoc.10.327

• oxidative cleavage of the vicinal diol unit in the latter to a formyl group (not isolated) followed by its in situ reduction with NaBH4 delivered the hydroxymethyl chain in 17. Hydrogenolytic removal of the two benzyl ether functionalities with Pearlman’s catalyst then afforded the tetrahydroxyindolizidine

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• ][11][12][13][14][15], hydrolysis and substitution reactions [16][17][18]. Filippo and co-workers [19][20][21][22] have extensively studied the substitution reactions of alkyl halides and tosylates; oxidative cleavage reactions and hydrolysis of esters. Frimer and co-workers [23][24] have studied its

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

• Yiyang Liu,
• Marc Liniger,
• Ryan M. McFadden,
• Jenny L. Roizen,
• Jacquie Malette,
• Corey M. Reeves,
• Douglas C. Behenna,
• Masaki Seto,
• Jimin Kim,
• Justin T. Mohr,
• Scott C. Virgil and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2014, 10, 2501–2512, doi:10.3762/bjoc.10.261

• prepared in excellent yield and ee by alkylation of carboxy-lactam 49 (see Scheme 11) [84]. Oxidative cleavage of the terminal double bond and subsequent reduction with LiAlH4 afforded N-benzylpiperidine-alcohol 56 [84]. Hydrogenolysis of the N-benzyl group and re-protection with di-tert-butyl dicarbonate

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• tricarballylic acid (105). The latter fragment would be accessed by conjugate addition of the anion of phosphonamide 28c to tert-butyl sorbate (106) to give intermediate 107 followed by oxidative cleavage of the chiral auxiliary (Figure 5 and Scheme 13). The preparation of 107 was performed as previously

• addition of trimethylsilylcyanide to the formed Schiff-base provided aminonitrile 168 as the major diastereomer (dr 95:5). Oxidative cleavage of the phenylglycinol moiety with Pb(OAc)4 liberated the amino-functionality and hydrolysis of the amide and nitrile under acidic conditions finally gave DCG-IV (162

• diastereomer (Scheme 21). Conversion of tert-butyl ester 170 into aldehyde 171 by a two-step protocol was followed by condensation with (R)-α-phenylglycinol and treatment of the formed Schiff base with trimethylsilylcyanide to afford α-aminonitrile 172 as major isomer (dr > 4:1). Oxidative cleavage with Pb(OAc

Synthesis and bioactivity of analogues of the marine antibiotic tropodithietic acid

• Patrick Rabe,
• Tim A. Klapschinski,
• Nelson L. Brock,
• Christian A. Citron,
• Paul D’Alvise,
• Lone Gram and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2014, 10, 1796–1801, doi:10.3762/bjoc.10.188

• . Oxidative cleavage of the glycol with NaIO4 resulted in a β-ketoester aldehyde that upon treatment with silica gel underwent an intramolecular aldol condensation to a mixture of 10a and 11a that were separable by column chromatography. Oxidation with DDQ gave tert-butyl tropone-2-carboxylate (12a) that was

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

• Nathan J. Gesmundo and
• David A. Nicewicz

Beilstein J. Org. Chem. 2014, 10, 1272–1281, doi:10.3762/bjoc.10.128

• to examine the scope of the reaction with respect to the diene structure. Miyashi’s 1,5-diene (2b; E1/2Ox = 1.22 V vs SCE [12]) afforded a 50% yield of the expected endoperoxide along with ~5% of a 1,4-dione, presumably from double oxidative cleavage of the 1,5-diene (Table 2, entry 1). Unfortunately

• , attempts to move away from 2b to less electron-rich dienes such as 2c, 2d and 2e (Table 1, entries 2–4), failed to produce any of the desired endoperoxide products and mainly oxidative cleavage adducts were observed. Given the lack of reactivity of this alkene substitution pattern, we turned our attention

• intermediate. The competing 6-endo cyclization mode and formation of distonic cation radical 9 ultimately provides access to the more stabilized cation radical 10, which undergoes oxidative cleavage to afford the corresponding α-allyl ketones (Scheme 4). In the absence of the geminal dimethyl group (2r, 2s