Synthesis and biological evaluation of 1,2-disubstituted 4-quinolone analogues of Pseudonocardia sp. natural products

• Stephen M. Geddis,
• Teodora Coroama,
• Suzanne Forrest,
• James T. Hodgkinson,
• Martin Welch and
• David R. Spring

Beilstein J. Org. Chem. 2018, 14, 2680–2688, doi:10.3762/bjoc.14.245

• strategy which granted access to remainder of the natural products 5–8, alongside offering more efficient synthesis of 1 and 4 [11]. Allylic alcohols 5 and 6 were accessed from a mutual precursor (constructed using methodology adapted from that reported by Bernini et al. [12]) using an acid-catalysed

• natural products. The chemistry developed towards the allylic alcohols 5 and 6, outlined in Scheme 1, seemed ideal to this end. A range of alkynes 10 could undergo Sonogashira coupling with the commercially available acid chloride 9. The resultant ynones 11 could then undergo conjugate addition with

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• regiodivergent carboxylation of allyl acetates in the presence of Mn as the reductant [26]. Mita and Sato found that Pd-catalyzed carboxylation of allylic alcohols proceeded using Et2Zn as the reducing agent [27]. The carboxylation of propargyl chloride was reported as one of the examples concerning the Ni

A challenging redox neutral Cp*Co(III)-catalysed alkylation of acetanilides with 3-buten-2-one: synthesis and key insights into the mechanism through DFT calculations

• Andrew Kenny,
• Alba Pisarello,
• Arron Bird,
• Paula G. Chirila,
• Alex Hamilton and
• Christopher J. Whiteoak

Beilstein J. Org. Chem. 2018, 14, 2366–2374, doi:10.3762/bjoc.14.212

• functionalisation approach in 43% yield from the Cp*Rh(III)-catalysed coupling of allylic alcohols with acetanilide through a redox-active mechanism (Scheme 1b) [21], thus requiring stoichiometric oxidant (Cu(OAc)2), whereas the new protocol described in this report is intended to provide a more attractive redox

• Cp*Rh(III)-catalysed coupling of allylic alcohols reported by Jiang and co-workers which requires the inclusion of 2.0 equivalents of Cu(OAc)2 for the same products [21]. With the optimised conditions in hand, the potential scope/limitations of the catalytic protocol were studied (Scheme 3

• Int 2ketone with the acetanilide (left) and benzamide substrates (right). (a) Our previously reported Cp*Co(III) redox-neutral coupling of 3-buten-2-one to benzamides, (b) previous oxidative alkylation of acetanilide through the coupling of allylic alcohols under Cp*Rh(III) catalysis, and (c) the Cp

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• intermediates in the synthesis of pharmaceuticals and various chemical entities such as allylic alcohols, benzoxathiepines, benzotiazepines, α-thioketones, α-substituted α,β-unsaturated enones, and β-hydroxysulfoxides [15]. Accordingly, a number of methodologies have been reported for their synthesis

Biocatalytic synthesis of the Green Note trans-2-hexenal in a continuous-flow microreactor

• Morten M. C. H. van Schie,
• Tiago Pedroso de Almeida,
• Gabriele Laudadio,
• Florian Tieves,
• Elena Fernández-Fueyo,
• Timothy Noël,
• Isabel W. C. E. Arends and
• Frank Hollmann

Beilstein J. Org. Chem. 2018, 14, 697–703, doi:10.3762/bjoc.14.58

• ]. Especially the availability as recombinant enzyme (enabling future at-scale production and protein engineering) and its promising activity on allylic alcohols make PeAAOx a promising starting point. Commercially available alcohol oxidases from Pichia pastoris and Candida boidinii showed no significant

Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ⁶-sulfanyl)acetic acid esters with aldehydes

• Anna-Lena Dreier,
• Andrej V. Matsnev,
• Joseph S. Thrasher and
• Günter Haufe

Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25

• formed as mixtures of (E)- and (Z)-isomers from SF5-substituted acetic acid esters of aliphatic terminal allylic alcohols at low temperature. At slightly elevated temperature, the latter diastereomers are transformed to γ,δ-unsaturated α-pentafluoro-λ6-sulfanyl alkanoic acids in an Ireland–Claisen

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• Scheme 10. β-Trifluoromethyl ketones could also be obtained from allylic alcohols 25 by a cascade trifluoromethylation/1,2-aryl migration. Yang, Xia and co-workers employed sodium triflinate under metal-free conditions with ammonium persulfate as the oxidant that was necessary to generate the CF3 radical

Base-promoted isomerization of CF₃-containing allylic alcohols to the corresponding saturated ketones under metal-free conditions

• Yoko Hamada,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 1507–1512, doi:10.3762/bjoc.13.149

• the toluene refluxing temperature, and utilization of the corresponding optically active substrates unambiguously demonstrated that this transformation proceeded in a highly stereoselective fashion. Keywords: allylic alcohols; chirality; computation; 1,3-proton shift; trifluoromethyl; Introduction

• this interesting and efficient protocol, computation was performed [7] for obtaining the rough indication of the acidity of both protons Ha and Hb in 1F. Moreover, the corresponding allylic alcohols 2F as well as their non-fluorinated counterparts 1H and 2H were also employed for comparison whose

• -O − E2X) in the case of propargylic (or allylic) alcohols, respectively, as the simple measure of destabilization. In the case of the non-fluorinated 1H and 2H series, as expected, a clear alkoxide preference was noticed irrespective of the carbon–carbon unsaturation pattern. For the corresponding

Studies directed toward the exploitation of vicinal diols in the synthesis of (+)-nebivolol intermediates

• Runjun Devi and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2017, 13, 571–578, doi:10.3762/bjoc.13.56

• number of cinchona alkaloid-derived ligands which allow the dihydroxylation of alkenes of almost all substitution patterns with high enantioselectivity. Noteworthy is that the SAD is not limited to only E-allylic alcohols in its choice of substrates as is the SAE process. Moreover, the SAD is much more

Selective synthesis of thioethers in the presence of a transition-metal-free solid Lewis acid

• Federica Santoro,
• Matteo Mariani,
• Federica Zaccheria,
• Rinaldo Psaro and
• Nicoletta Ravasio

Beilstein J. Org. Chem. 2016, 12, 2627–2635, doi:10.3762/bjoc.12.259

• reaction of optically active (R)-1-phenylethanol gave a completely racemic compound (Scheme 1). Unfortunately allylic alcohols gave unreproducible results. However, in the case of cinnamyl alcohol (1i) we could obtain a fairly good selectivity to the product of the thiol–ene reaction 3p (Scheme 2). The

• ] dispersed on silica is active in promoting the substitution of adamantanol, cinnamyl and benzyl alcohols with thiols whereupon significative amounts of Zr salt are required; whereas Wu and Han have shown that Ga(OTf)3 is an effective catalyst for the substitution of a wide range of benzylic and allylic

• alcohols with phosphorothioic acid and with a wide range of alcohols with various sulfur nucleophiles in an effective way [16]. On the contrary SmCl3 promotes the formation of thioethers only from 2-cyclohexen-1-ol and geraniol with thiophenol [17] while the use of cationic diruthenium complexes is limited

Synthesis of polyhydroxylated decalins via two consecutive one-pot reactions: 1,4-addition/aldol reaction followed by RCM/syn-dihydroxylation

• Michał Malik and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2016, 12, 2602–2608, doi:10.3762/bjoc.12.255

• allylic alcohols as substrates in Mitsunobu reactions can be a challenging task, some successful examples can be found in the literature [49][50]. However, the reaction with benzoic acid did not proceed at all, whereas application of p-nitrobenzoic acid yielded a complicated mixture of products. Therefore

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• ], and palladium (0, II) [9][10] as the catalyst or by converting the allylic alcohols into esters of inorganic acids, e.g., As2O3 [11], B2O3 [12], CO2 [13][14]. More recently the Lewis acids, such as, Ti(OiPr )4 [15], BEt3 [16][17][18][19], BPh3 [20], SnCl2 [21], and FeCl3 [22], have also been reported

• allylation of a variety of active methylene compounds [29], aldehydes [30], ketones [31], and imines [32] with only common allylic alcohols. As part of an ongoing program studying the behavior of MBH derivatives [33] towards β-dicarbonyl compounds, our research group [34][35][36][37] has reported an

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

• rearrangements and related processes play an important role in the chemistry of oxidation processes. Thus, the key reagent in the Sharpless epoxidation of allylic alcohols [48] and in the manufacture of propylene oxide via the Prilezhaev reaction [49][50][51] is tert-butyl hydroperoxide. In industry, phenol and

Selective bromochlorination of a homoallylic alcohol for the total synthesis of (−)-anverene

• Frederick J. Seidl and
• Noah Z. Burns

Beilstein J. Org. Chem. 2016, 12, 1361–1365, doi:10.3762/bjoc.12.129

• Frederick J. Seidl Noah Z. Burns Department of Chemistry, Stanford University, Stanford, California 94305, USA 10.3762/bjoc.12.129 Abstract The scope of a recently reported method for the catalytic enantioselective bromochlorination of allylic alcohols is expanded to include a specific

• generality and scope of such catalytic enantioselective methods may be large, limitations often exist. In the case of the SAE, allylic alcohols are viable substrates, but homoallylic alcohols undergo epoxidation at slower rates and with diminished yields and enantioselectivities [3]. This particular

• able to override inherent substrate regioselectivity [7]. This development vastly expanded the substrate scope to include a larger subset of alkyl-substituted allylic alcohols (Scheme 1, top); the relative and absolute stereochemical configurations of all resulting bromochlorides have been assigned and

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

• . [38] isoprene was reacted with N-bromosuccinimide (NBS, 44) in water at 8–10 °C for 2 h. The reaction afforded a mixture of two allylic bromides and two allylic alcohols in a combined 42% yield, these were tentatively assigned as (E)-45, (Z)-46, rac-47 and rac-48 (route A, Scheme 7). All attempts at

• , separable allylic alcohols and allylic iodides. Interestingly this alternative protocol afforded only two of the possible four products. Thus terminal alkene derived 1-iodo-2-methylbut-3-en-2-ol (rac-53) and 2-iodo-2-methylbut-3-en-1-ol (rac-54) were afforded in a 9:1 ratio, respectively, and a pleasing 72

• reported [48]. Taking (E)-58 and (Z)-59 forward their reduction to (E)-60 and (Z)-61 using DIBAL-H (−78 °C) was uncomplicated. The corresponding (E)- and (Z)-allylic alcohols were afforded in 87% and 81% yields, respectively. The physicochemical properties of (E)-60 were essentially identical to those

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• reaction [34]. By installation of a triflyloxy group in the indole 5-position, Pd-catalyzed cyclization also would become possible. As an alternative to the cyclization of enones, Lewis acid-induced cyclizations of allylic alcohols could afford the desired cyclopenta[f]indole system (C, D). Here, it was

Recent advances in copper-catalyzed asymmetric coupling reactions

• Fengtao Zhou and
• Qian Cai

Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280

• functionalized chiral building blocks such as allylic alcohols, amines etc. [79]. Sawamura et al. [80] developed a highly enantioselective copper-catalyzed asymmetric allylic substitution with diboronates to afford chiral allylboronates (Scheme 33). McQuade et al. [81] reported a copper/NHC-catalyzed allylic

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• allows the formation of E- or Z-configured cyclononenes. Additionally, the intramolecular palladium-catalyzed cyclization of haloalkenes with organoboranes affords cyclononenes with retention of the double bond configuration [28]. The corresponding allylic alcohols can be prepared by a Nozaki–Hiyama

Preparation of conjugated dienoates with Bestmann ylide: Towards the synthesis of zampanolide and dactylolide using a facile linchpin approach

• Jingjing Wang,
• Samuel Z. Y. Ting and
• Joanne E. Harvey

Beilstein J. Org. Chem. 2015, 11, 1815–1822, doi:10.3762/bjoc.11.197

• aldehyde. Primary and secondary alcohols, including allylic alcohols, are suitable substrates; the newly formed alkene has an E-geometry. Strategically, this represents a highly efficient route to unsaturated polyketide derivatives. A linchpin approach to the synthesis of a major fragment of the natural

Influence of bulky yet flexible N-heterocyclic carbene ligands in gold catalysis

• Alba Collado,
• Scott R. Patrick,
• Danila Gasperini,
• Sebastien Meiries and
• Steven P. Nolan

Beilstein J. Org. Chem. 2015, 11, 1809–1814, doi:10.3762/bjoc.11.196

• characterised. The impact of varying the length of the alkyl chain of the ligands in gold-promoted transformations has been explored. All gold complexes were shown to be active in water inclusive reactions (alkyne and nitrile hydration) and in the synthesis of homoallylic ketones from allylic alcohols and

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• further oxidation. SCPC oxidations that take place with varying success include toluene to benzaldehyde and benzoic acid [25], cyclohexane to cylohexanone [26], benzylic and allylic alcohols to carbonyl compounds [27] and alkene epoxidations [28]. Conventional syntheses of coumarins, which are important

Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

• Philipp Röse,
• Steffen Emge,
• Jun-ichi Yoshida and
• Gerhard Hilt

Beilstein J. Org. Chem. 2015, 11, 174–183, doi:10.3762/bjoc.11.18

• generated selenium- or iodonium cations. Results and Discussion Cobalt-catalysed 1,4-hydrovinylation of allylic alcohols For the successful application of 1,4-dienes in the electrochemical reactions, 1,4-dienes with additional internal nucleophiles, such as an alcohol group, were envisaged and those 1,4

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• synthesized also from aromatic aldehydes, α,β-unsaturated aldehydes, or allylic alcohols in the presence of the DDQ (2,3-dichloro-5,6-dicyanobenzoquinone)/amberlyst-15 system in a methanol/toluene mixture under microwave irradiation [171]. Methyl, ethyl, and isopropyl benzoates were prepared from benzaldehyde

Selective allylic hydroxylation of acyclic terpenoids by CYP154E1 from Thermobifida fusca YX

• Anna M. Bogazkaya,
• Clemens J. von Bühler,
• Sebastian Kriening,
• Alexandrine Busch,
• Alexander Seifert,
• Jürgen Pleiss,
• Sabine Laschat and
• Vlada B. Urlacher

Beilstein J. Org. Chem. 2014, 10, 1347–1353, doi:10.3762/bjoc.10.137

• Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany 10.3762/bjoc.10.137 Abstract Allylic alcohols are valuable precursors in the synthesis of pharmaceutical intermediates, agrochemicals and natural products

• -box for allylic hydroxylation in synthetic chemistry. Keywords: allylic hydroxylation; cytochrome P450; natural products; protein engineering; regiochemistry; terpenoids; Introduction Direct allylic hydroxylation yielding highly valuable allylic alcohols has been recognised for a while as one of the

• most oxyfunctionalizations [1]. Allylic alcohols can further be exploited for the synthesis of pharmaceutical intermediates, agrochemicals and natural products [2][3][4]. Various chemical catalysts including enzyme mimetica have been designed, characterised and applied for catalytic allylic

Synthesis of a sucrose dimer with enone tether; a study on its functionalization

• Zbigniew Pakulski,
• Norbert Gajda,
• Magdalena Jawiczuk,
• Jadwiga Frelek,
• Piotr Cmoch and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2014, 10, 1246–1254, doi:10.3762/bjoc.10.124

• selective and provides the corresponding allylic alcohols with the R configuration at the newly created stereogenic center, as the only products. This can be rationalized assuming the cyclic model of such reduction [25] shown in Scheme 2. We expected, therefore, also very high selectivity in the reduction