Stereoselective syntheses of 3-aminocyclooctanetriols and halocyclooctanetriols

• Emine Salamci and
• Yunus Zozik

Beilstein J. Org. Chem. 2021, 17, 705–710, doi:10.3762/bjoc.17.59

• are reported. Reduction of cyclooctene endoperoxide, obtained by photooxygenation of cis,cis-1,3-cyclooctadiene, with zinc yielded a cyclooctene diol followed by acetylation of the hydroxy group, which gave dioldiacetate by OsO4/NMO oxidation. The cyclooctane dioldiacetate prepared was converted to

• should have a cis configuration relative to the protons H-3 and H-4. Next, the reduction of azidotriol 10 by hydrogenation afforded the target aminotriol 12 in 95% yield. For the synthesis of the other aminocyclooctanetriol 18, the diol 6a [33] was reacted with m-CPBA to give trans-epoxide isomer 13 [33

• method for the synthesis of a novel chlorocyclooctanetriol isomer, epoxy-diol 22, which was synthesized in our previous work [31], was hydrolysed by HCl(g) in MeOH, resulting in the formation of two chlorocyclooctanetriol isomers 23 and 24 in an 85:15 ratio (1H NMR) in 96% combined yield (Scheme 5

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• )stoichiometric amounts of diol cleaving agents, other than EG (for instance, PD [239], DEG [240][241]). As a consequence, the depolymerisation step usually results in complex mixtures of oligomers. Moreover, reacting diols may be unstable under the reaction conditions adopted. Hence, if used in excess, a

• chemical recycling to produce novel polyesters [245]. In this process, isosorbide was used as depolymerising diol to give a mixture of differently composed oligomers, whereas succinic acid was added in the second step as polymerising comonomer (Scheme 7). Both steps were efficiently catalysed by

Designed whole-cell-catalysis-assisted synthesis of 9,11-secosterols

• Marek Kõllo,
• Marje Kasari,
• Villu Kasari,
• Tõnis Pehk,
• Ivar Järving,
• Margus Lopp,
• Arvi Jõers and
• Tõnis Kanger

Beilstein J. Org. Chem. 2021, 17, 581–588, doi:10.3762/bjoc.17.52

• chemistry and synthetic biology. Stereo- and regioselective hydroxylation at C9 (steroid numbering) is carried out using whole-cell biocatalysis, followed by the chemical cleavage of the C–C bond of the vicinal diol. The two-step method features mild reaction conditions and completely excludes the use of

• to its toxicity, the oxidation rate affording trans-diols was very slow in comparison to that for cis-diols. Using an even longer reaction time and stoichiometric amount of the reagent, diol 5 was not oxidized to the corresponding dicarbonyl compound 8. However, using NaOCl·5H2O as an oxidant [31

• ], diols 5 and 6 were effectively converted to the corresponding 9,11-secosterols 8 and 9 within one hour at 0 °C (Scheme 3). Compound 8 was isolated as 2:1 mixture together with starting diol 5 and purified further by preparative TLC. Compound 9 was isolated as a single product in 87% yield. Conclusion We

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• [81]. The authors obtained the chiral monoacetate intermediates (R)-78 and (S)-80 by lipase-catalyzed methods. The lipase-catalyzed asymmetric transesterification of prochiral diol 77 and the deacetylation of the prochiral diacetate 79 resulted in the formation of the (R)-monoacetate (R)-78 and (S

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• Lewis acid, while the utilization of 1.5 equivalents led to a significant overreaction with the predominant formation of 5-bromobenzene-1,3-diol (59%) together with a smaller amount of the required product 8 (30%). The subsequent protection with the TBS group yielded the known aryl bromide 9a [24] with

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• ] (“Cyclodextrin–gold nanocluster decorated TiO2 enhances photocatalytic decomposition of organic pollutants” by H. Zhu et al., J. Mater. Chem. A vol. 6, © 2017); permission conveyed through Copyright Clearing Center, Inc. Visible-light-driven conversion of benzyl alcohol to H2 and a vicinal diol or to H2 and

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• transformed into (−)-101 using a three-step sequence. Upon iodination of (−)-101 produced iodide (+)-102 in excellent yield. Deiodination of (+)-102 followed by regioselective dihydroxylation with Sharpless’ AD mix-β reagent [64][65] provided diol (−)-103 as a mixture of stereoisomers. Significantly, the diol

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• second generation Grubbs catalyst 57 in 99% yield. The azabicyclic system (+)-51 underwent dihydroxylation with the OsO4-NMO system to form diol (+)-52 as the only product in 97% yield. Diol (+)-52 was regioselectively protected in the presence of tert-butyldimethylsilane triflate, and triethylamine

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• ] was protected as the benzyl ether then subjected to a Sharpless asymmetric dihydroxylation reaction to furnish the diol 8 in modest yield. The diol 8 was then converted into the cyclic sulfate 9, which was ring-opened using TBAF to furnish the fluorohydrin 10. A Mosher ester analysis of the

Design and synthesis of a bis-macrocyclic host and guests as building blocks for small molecular knots

• Elizabeth A. Margolis,
• Rebecca J. Keyes,
• Stephen D. Lockey IV and
• Edward E. Fenlon

Beilstein J. Org. Chem. 2020, 16, 2314–2321, doi:10.3762/bjoc.16.192

• ), whereas host 1 and guest 3 would lead to a 75 backbone-atom trefoil (and unknotted macrocycle). Results and Discussion The synthesis of bis-macrocyclic host 1 began by breaking the symmetry of naphthalene-1,5-diol (4) by alkylation of one of the alcohols with 2-azidoethyl mesylate to yield azide 5 in 27

• % yield (Scheme 1). Alkylation of 5 with 1,2-dibromoethane provided key intermediate azido-bromide 6 in 60% yield. This two-step route to 6 is efficient, but the 16% overall yield was lower than desired. An alternate route began by converting diol 4 to bis(2-hydroxyethoxy)naphthalene 7 in 92% yield by

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• on subsequent Tamao–Fleming oxidation provided the exo-diol 18 in an overall good yield with 99% enantiomeric excess (Scheme 3). Furthermore, the diol 18 was converted into the corresponding diketone 19 using pyridinium chlorochromate (PCC) as an oxidizing agent. Interestingly, they have also

Synthesis of 6,13-difluoropentacene

• Matthias W. Tripp and
• Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

• subsequent reduction step using NaBH4 to diol 13 was performed without further purification of the quinone. The low yield for the formation of 13 seems to be an intrinsic instability of its ortho-fluorobenzylic alcohol moiety. Moreover, the compound quantitatively decomposes to 6,13-pentacenequinone 15 in

• 14 then rapidly decomposes to 6,13-pentacenequinone (15) after elimination of HF. The final aromatization of diol 13 to the target molecule 5 proceeded smoothly in 74% yield using SnCl2 in 1,4-dioxane and aqueous HCl [11][12]. F2PEN 5 can be stored under inertgas atmosphere at −20 °C for a month

• -difluoroanthracene. This strategy could be applicable for the synthesis of differently substituted 6,13-difluoropentacenes as well. Structures of pentacene and fluorinated pentacenes. UV–vis spectrum of F2PEN 5 in CH2Cl2. Retrosynthetic analysis of F2PEN 5. Synthesis of F2PEN 5. Decomposition of diol 13 in solution

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

• Clément Q. Fontenelle,
• Thibault Thierry,
• Romain Laporte,
• Emmanuel Pfund and
• Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

• lactone product 15 (containing 10% of ester Z-13) and proved successful with phosphonolactone 21 being isolated in 77% yield after column chromatography (Scheme 7). To access tetrasubstituted alkenes, reduction of 21 to generate diol 22 was explored with lithium borohydride in Et2O. However, the reaction

• was slow at 20 °C and did not progress beyond 50% conversion even after the addition of excess LiBH4. After purification by flash chromatography starting lactone 21 was obtained in 49% yield and the desired diol 22 in 47% yield. When the reaction was carried out in refluxing THF, a complete conversion

• precursors of ACN (VII) bearing different functional groups (Scheme 9). A particular focus was applied to the preparation of the phosphonate 29, a precursor of VII that is not accessible from diol VIII. First, starting from pure alkene E-9, the introduction of a protected alcohol as a mimic of the naturally

Stereoselective Biginelli-like reaction catalyzed by a chiral phosphoric acid bearing two hydroxy groups

• Xiaoyun Hu,
• Jianxin Guo,
• Cui Wang,
• Rui Zhang and
• Victor Borovkov

Beilstein J. Org. Chem. 2020, 16, 1875–1880, doi:10.3762/bjoc.16.155

• BINOL, 2,2-dimethyltetraphenyl-1,3-dioxolane-4,5-dimethanol (TADDOL) was also widely used as a C2 chiral diol. However, TADDOL-derived phosphoric acids were not comprehensively investigated as catalysts in Biginelli and Biginelli-like reactions yet. The first example of their successful application was

One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: theoretical evidence for an asynchronous concerted pathway

• Esra Demir,
• Ozlem Sari,
• Yasin Çetinkaya,
• Ufuk Atmaca,
• Safiye Sağ Erdem and
• Murat Çelik

Beilstein J. Org. Chem. 2020, 16, 1805–1819, doi:10.3762/bjoc.16.148

• reaction with the metal complexes or catalysts, and the reaction of a diol with toxic phosgene are the most common processes [16][17][33][34][35][36]. CSI, a highly reactive and versatile isocyanate, reacts with epoxides to give five-membered cyclic carbonates and oxazolidinones [37][38][39]. In 1984

Synthesis of the tetrasaccharide repeating unit of the O-specific polysaccharide of Azospirillum doebereinerae type strain GSF71^T using linear and one-pot iterative glycosylations

• Arin Gucchait,
• Pradip Shit and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 1700–1705, doi:10.3762/bjoc.16.141

• the product in CH3CN (10 mL) was added HClO4-SiO4 (50 mg) and the mixture was allowed to stir at room temperature for 15 min. Then, the reaction mixture was filtered and the filtrate was concentrated under reduced pressure. To a solution of the diol in CH2Cl2 (5 mL) were added pyridine (100 μL, 1.24

NHC-catalyzed enantioselective synthesis of β-trifluoromethyl-β-hydroxyamides

• Alyn T. Davies,
• Mark D. Greenhalgh,
• Alexandra M. Z. Slawin and
• Andrew D. Smith

Beilstein J. Org. Chem. 2020, 16, 1572–1578, doi:10.3762/bjoc.16.129

• as a nucleophile gave the corresponding ester, however, this product proved unstable to purification. Generation of the ester in situ, followed by subsequent reduction with LiAlH4, gave the diol 11 in 48% isolated yield as a single diastereoisomer in 96:4 er. Subsequent variation of the electronic

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• 1966 [32]. They treated 3,5-dichloropentan-2-ol (9) with K2S to produce 1-(thietan-2-yl)ethan-1-ol (10) in 65% yield (Scheme 1). In 2007, Nishizono and co-workers used 2,2-bis(bromomethyl)propane-1,3-diol (11) as starting material to prepare thietanose nucleosides 2 and 14. They first carried out a

• as inhibitor of kinases, insecticides, and acaricides, its sulfur analogue, 6-amino-2-thiaspiro[3,3]heptane (28) was prepared from the cheap starting material 2,2-bis(bromomethyl)propane-1,3-diol (11). Compound 11 was converted into 3-(tert-butoxycarbonyl)-1,1-bis(hydroxymethyl)aminocyclobutane (25

• converted to the final thietane-containing spironucleoside 46 [41] (Scheme 10). In 2011, Nishizono and co-worker synthesized two anomeric thietanose nucleosides with (Z)-but-2-ene-1,4-diol (47) as the starting material. They first converted the diol 47 into dimethanesulfonates 48 of 1,5-dibenzyloxypentane

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• contracted and expanded their pores in the presence of guest gases [42]. In the limiting case, the framework may even become partially dissolved in a polar solvent. The CAHOF F-1 was also catalytically active for the conversion of styrene oxide (2) into the diol 4 (Table 1, runs 8–14). This reaction was a

• reaction was stirred. After 3 (or 24) hours, the solid catalyst was filtered, the layers were separated, evaporated, and analyzed. The aqueous layer contained only the diol 4 and some dissolved F-1. The organic mixture contained a mixture of the epoxide 2 and the diol 4. Therein, the catalyst was a

• recovered by evaporating the aqueous layer, adding dichloromethane to the residue and filtering the insoluble catalyst. The efficiency of the multiphase reactions should depend on the rate of stirring the reaction. The runs 8–12 in Table 1 illustrated the dependence of the yield of the diol 4 on the

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• of type III 2.1. Fluorination of protected (1R,2R)-2-amino-ʟ-phenylpropane-1,3-diol Recently, Okuda et al. reported the synthesis of (3R)-3-fluoro-ʟ-phenylalanine (121) from (1R,2R)-2-amino-ʟ-phenylpropane-1,3-diol (116). Thus, Boc-protection of the amine group in 116 followed by the protection of

• -difluorophenylalanine 115. Synthesis of β-fluorophenylalanine via 2-amino-1,3-diol derivatives. Synthesis of β-fluorophenylalanine derivatives via the oxazolidinone chiral auxiliary 122. Synthesis of β-fluorophenylalanine from pyruvate hemiketal 130. Synthesis of β-fluorophenylalanine (136) via fluorination of β

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• α-hydroxybenzyl radical 90, which then coupled, forming the 1,2-diol 92 (Scheme 23). In 2014, Melchiorre and co-workers found that 4-anisaldehyde (52) could efficiently catalyze the intermolecular atom transfer radical addition (ATRA) of the haloalkanes 93 to the olefins 94 under irradiation with a

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• of cyclopentene-1,4-diol that was obtained by the enzymatic desymmetrization of the corresponding diacetate, an enyne metathesis precursor was accessed by a Mitsunobu-type coupling reaction with propargylic amide. The ring-rearrangement metathesis (RRM) of this enyne precursor was carried out using

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• 327. In addition, the formation of an anti-1,2-diol with high enantioselectivity is also another outcome resulting from this protocol (Scheme 52) [95]. Catalytic Cu-mediated conversions of (Z)-3-arylallylic phosphates 332 to nonracemic trans-2-aryl and -heteroaryl-substituted cyclopropylboronates 333

Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment

• Jan Geldsetzer and
• Markus Kalesse

Beilstein J. Org. Chem. 2020, 16, 670–673, doi:10.3762/bjoc.16.64

• ). A subsequent transesterification under mild conditions with Bu2SnO provided dihydroxy ester 7 in 72% yield. The 1,3-diol in 7 was methylated with an excess of the Meerwein reagent and TIPDS-removal afforded ester 9 in good yields. A double TBS-protection and liberation of the primary alcohol

Synthesis of disparlure and monachalure enantiomers from 2,3-butanediacetals

• Adam Drop,
• Hubert Wojtasek and
• Bożena Frąckowiak-Wojtasek

Beilstein J. Org. Chem. 2020, 16, 616–620, doi:10.3762/bjoc.16.57

• 19 instead. This compound was obtained from both aldehyde 15 and its precursor ethyl thioester methyl ester 14, respectively (Scheme 3). Both substrates 14 and 15 were reduced to the corresponding diol 17 with lithium aluminum hydride with 73% or 83% yield, respectively. Next, the selective

• ), and (−)-monachalure (4) from diols 5–8. Isomerization of trans-2,3-butanediacetals 9–11 to cis-2,3-butanediacetals 12–14. Synthesis of diol 17 and its subsequent modifications. Synthesis of (+)-disparlure (1) and (+)-monachalure (2). Synthesis of (−)-disparlure (3) and (−)-monachalure (4). Conditions