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

• -disubstituted olefin and reductive epoxide ring-opening giving triol 18. After oxidation of the primary and the secondary alcohols with Dess–Martin periodinane, the remaining tertiary alcohol was protected as a MOM ether and the silyl ether protecting group was removed. The obtained intermediate 19 was then a

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• gives access to 6A-mono- and 6A,D diol (3) in high yields and purity, and by extension of this method further deprotection on the primary [10][11][12] and secondary rim can be made [13][14][15]. The reaction of 2 with DIBAL leads quite rapidly to diol 3 and then much slower to triol 4 and tetrol 5

• identity of protective groups on the secondary rim influence the reaction at the primary rim significantly, most probably by a collective inductive effect. When the reaction of 7 with DIBAL was carried out at higher temperature further debenzylation was observed with, according to MS, a triol 9 being

• formed from 8. When 7 was reacted with 1.5 M DIBAL in toluene at 60 °C for 24 hours an almost equal amount of 8 and 9 was present (Table 1, entry 3) and 27% of triol 9 together with 32% of 8 was isolated. A tetrol 10 was obtained upon even longer reaction of 7: If reacted with 0.1 M DIBAL in toluene for

Terpenoids from Glechoma hederacea var. longituba and their biological activities

• Dong Hyun Kim,
• Song Lim Ham,
• Zahra Khan,
• Sun Yeou Kim,
• Sang Un Choi,
• Chung Sub Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2022, 18, 555–566, doi:10.3762/bjoc.18.58

• displayed 26 carbon signals including two oxygenated carbons (δC 85.8 and 72.4), an oxygenated quaternary carbon (δC 79.5), and a glucopyranosyl unit (δC 101.9, 78.3, 77.7, 75.2, 71.9, and 63.0) (Table 3). These 1H and 13C NMR spectra of 4 were similar to those of ent-kauran-3α,12α,16α-triol except for an

• identified as ent-kauran-3α,12α,16α-triol 3-O-β-ᴅ-glucopyranoside. Compound 5 was obtained as a colorless gum. Based on its HRESIMS and NMR data, its molecular formula was determined as C28H46O9 (m/z 549.3031 [M + Na]+, calcd for C28H46O9Na, 549.3040). The 1H NMR spectrum of 5 showed four methyl groups [δH

• (13.8 min) (Supporting Information File 1, Figure S43). Thus, the structure of compound 5 was established as ent-kauran-3α,12α,16α-triol 3-O-β-ᴅ-(2'-O-acetyl)-glucopyranoside. By comparing the NMR and MS data with those reported in literature, the four known compounds 6–9 were identified as ent-kauran

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• derivative 11 was obtained by cyclization with 3 equivalents of potassium O-ethyl xanthate. It was then treated with a methanolic ammonia solution to give triol compound 12. The protection of the cis-2,3-vicinal hydroxy groups of 12 with an isopropylidene, followed by benzoylation, gave compound 13. Using 2

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• introduced by the addition of a protected propargyl alcohol to the epoxide derived from triol 109. The furan ring is formed by an acid-catalyzed intramolecular cyclization of the alcohol intermediate obtained from the Noyori reduction of α,β-unsaturated ketone 110. This compound is eventually constructed

• treated with an acid to remove the isopropylidene protection and induce intramolecular cyclization to the 2’,5’-syn-furan 109 in 80% yield. This triol was subjected to excess sodium hydride and tosylating agent, and the mixture was allowed to react for 90 minutes, after which benzyl bromide was added to

• furnish the terminal epoxide 115 in 85% from 109. Then, the epoxide ring was opened with deprotonated propargylic ether 116. Global removal of the PMB functionality with DDQ gave triol 117. The partial reduction of the triple bond in 117 to the (Z)-olefin derivative was achieved using Lindlar catalyst and

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• , using our previously published methodology in an overall yield of 8% over 8 steps (Scheme 1) [1]. An alternative strategy for the synthesis of 4 was developed so as to avoid a cumbersome continuous extraction step of a triol associated with the established method, in addition to improving the overall

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• tetroxide-mediated dihydroxylation in the presence of N-methylmorpholine N-oxide (NMMO) afforded 11 in 90% yield. Finally, the regioselective transferuloylation of the primary hydroxy group of the triol derivative 11 with Lipozyme® TL IM was performed, and the expected chromogenic substrate 12 was isolated

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

• -Leopoldshafen, Hermann-von-Helmholtz-Platz 1, Germany 10.3762/bjoc.17.22 Abstract The total synthesis of decarboxyaltenusin (5’-methoxy-6-methyl-[1,1’-biphenyl]-3,3’,4-triol), a toxin produced by various mold fungi, has been achieved in seven steps in a yield of 31% starting from 4-methylcatechol and 1-bromo

• -methyl-[1,1’-biphenyl]-3,3’,4-triol (1, Scheme 1) has been first mentioned 1974 as a reduction and decarboxylation product of dehydroaltenusin [1]. As the compound has later been isolated from Ulocladium sp. [2], Nigrospora sphaerica, Phialophora sp. [3], Penicillium pinophilum SD-272 [4], Alternaria sp

• product, but purification and isolation of the product by column chromatography was not possible ‒ neither with conventional nor with reversed phase methods. It turned out that the high polarity of the triol complicated its separation from other polar side products. To circumvent this problem, we decided

Influence of the cis/trans configuration on the supramolecular aggregation of aryltriazoles

• Sara Tejera,
• Giada Caniglia,
• Rosa L. Dorta,
• Andrea Favero,
• Javier González-Platas and
• Jesús T. Vázquez

Beilstein J. Org. Chem. 2019, 15, 2881–2888, doi:10.3762/bjoc.15.282

• , these gels were stable for several months in sealed vials, although they could be disrupted by agitation or heating. However, the gel state could be restored through cooling. The triol 9 (trans) did not lead to any gel, while its α-anomer 10 (cis) produced translucent and transparent gels, respectively

Genome mining in Trichoderma viride J1-030: discovery and identification of novel sesquiterpene synthase and its products

• Xiang Sun,
• You-Sheng Cai,
• Yujie Yuan,
• Guangkai Bian,
• Ziling Ye,
• Zixin Deng and
• Tiangang Liu

Beilstein J. Org. Chem. 2019, 15, 2052–2058, doi:10.3762/bjoc.15.202

• two new alkane derivatives colisiderin A and (7E,9E)-undeca-7,9-diene-2,4,5-triol [35] and from the organic extract of the red alga Laurencia obtusa [36]. However, to the best of our knowledge, ours is the first report of these brasilane-type sesquiterpenes obtained via biosynthetic genes. Metal ion

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• debenzylation followed by acylation provided enantiomerically pure (S)-linezolid ((S)-107). 2-Amino-1,3,4-triols ᴅ-ribo-Phytosphingosine ((2S,3S,4R)-2-aminooctadecane-1,3,4-triol, (2S,3S,4R)-110) appears to be the most common from other stereoisomeric phytosphingosines which are present in many species and show

Efficient resolution of racemic crown-shaped cyclotriveratrylene derivatives and isolation and characterization of the intermediate saddle isomer

• Sven Götz,
• Andreas Schneider and
• Arne Lützen

Beilstein J. Org. Chem. 2019, 15, 1339–1346, doi:10.3762/bjoc.15.133

• 1984 [62]. At that time, they converted the racemic triol into diastereomeric triesters upon reaction with (R)-(+)-2-phenoxypropionic acid, separated those via column chromatography, and received the desired enantiomers upon reductive cleavage of the esters. Similar synthetic approaches through the

First synthesis of cryptands with sucrose scaffold

• Patrycja Sokołowska,
• Michał Kowalski and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2019, 15, 210–217, doi:10.3762/bjoc.15.20

• . This goal can be realized starting from sucrose triol 2 as shown in Figure 3. The first approach consists of a connection of the C1’-position of an intermediate aza-crown ether 12 with the secondary nitrogen atom present in a linker (route a in Figure 3). Another one (route b in Figure 3) involves a

• direct coupling of all three positions: C1’,C6, C6’. Recently we have proposed a convenient method for the conversion of triol 2 into a number of sucrose macrocycles having various substituents at the C1’-position [17][18]. Modification of these synthetic routes should allow, eventually, the preparation

• Scheme 3 can be also applied to prepare cryptands with larger cavities. This required an elongation of all three terminal positions (at C1’,C6,C6’) by a longer linker. Thus, reaction of triol 2 with bis(chloroethyl) ether provided derivative 21 in good yield. Replacement of the chlorine atoms for iodine

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• C–F amination reactions employing water/isopropanol [3] and triols [4][5] as hydrogen-bond donor activators. Through these studies, the authors suggested that multiple donors (even when using a triol) surround the fluorine atom of the benzyl fluoride, thus stabilising the transition state through

• Paquin [3][4][5]. Unfortunately, N-methylbenzylamine (Table 2, entry 3) afforded a product 7 that did not resolve by 2H NMR, and thus the ee could not be determined. Changing the activator from water/isopropanol to tris(hydroxymethyl)propane was anticipated to increase the stability of the triol–benzyl

• fluoride complex, and hence a tendancy towards an associative mechanism was expected. However, on performing the reactions with nitrogen nucleophiles (Table 2, entries 6 and 8) and the triol as the hydrogen bond donor, slightly lower ee’s were obtained relative to those obtained using the same nucleophiles

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

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

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• HWE olefination (Scheme 5). The (E)-monofluoroalkene was thus obtained in an excellent selectivity using n-butyllithium in tert-butyl methyl ether. The resulting ester 21 was reduced using lithium aluminum hydride, and treatment with tartaric acid deprotected the OBO, thus providing the free triol 22

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

• 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

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

• would be the non-requirement of any protecting group to construct the chroman ring. To test this seemingly straightforward approach, we initially attempted to synthesize (±)-2 utilizing the cyclization of (±)-triol 14 (Scheme 2) as the key step. Thus, commercially available 2,5-difluorobenzaldehyde (10

• the resulting crude aldehyde with Ph3P=CHCO2Et provided (E)-α,β-unsaturated ester 12 (80% over two steps). A further DIBAL-H (2.5 equiv, 0 °C) reduction of 12 delivered (E)-allylic alcohol 13 (90%) which was then dihydroxylated under Upjohn conditions to obtain triol (±)-14 (92%). With access to

• /DMF (80 °C), NaH/DMSO (100 °C) and KOt-Bu/toluene (110 °C) did not lead to any conversion. However, more forcing conditions such as NaH/NMP (130 °C) resulted in a to partial decomposition of the starting material. These results indicated that an intramolecular SNAr reaction of triol (±)-14 to form

Total synthesis of a Streptococcus pneumoniae serotype 12F CPS repeating unit hexasaccharide

• Peter H. Seeberger,
• Claney L. Pereira and
• Subramanian Govindan

Beilstein J. Org. Chem. 2017, 13, 164–173, doi:10.3762/bjoc.13.19

• blocks 10 and 7 [27] in a dichloromethane–ether (enables alpha selectivity) mixture in 56% yield (Scheme 4). Removal of the silyl ether and benzylidene groups of 19 yielded triol 20 before benzylation afforded disaccharide thioglycoside building block 21. Activation of disaccharide 21 resulted in the

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

• reduction of the azide to an amine) affording a crude product which was directly reacted with CbzCl to afford compound 19 (Scheme 5). Compound 19 on reaction with ceric ammonium nitrate (deprotection of PMP ether) followed by acetyl protection of the resultant triol using Ac2O in pyridine gave triacetate

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

• + 2] cycloaddition (Scheme 12) [60]. The synthetic route commenced with known aldehyde 119 which was converted to triol 120 in five steps (Scheme 13). The introduction of the benzyl ether next to the alkyne moiety was necessary to control the stereochemical outcome of the key annulation, and further

Synthesis of novel N-cyclopentenyl-lactams using the Aubé reaction

• Madhuri V. Shinde,
• Rohini S. Ople,
• Ekta Sangtani,
• Rajesh Gonnade and
• D. Srinivasa Reddy

Beilstein J. Org. Chem. 2015, 11, 1060–1067, doi:10.3762/bjoc.11.119

• explained by the reagent approach from the opposite side of both substituents present on the cyclopentene ring. We have assigned the structure based on the spectral data (see Experimental). In addition, crystals of the triol (±)-12 were obtained and single crystal X-ray analysis further established the

• and our initial designs. ORTEP plot of triol (±)-12. The Aubé reaction and its selected applications. Top: synthesis of azido alcohol derivative 3 and bottom: structural elucidation of the minor diastereomer. Aubé reaction of cylopentenyl azido alcohol 3 with cyclohexanone. Substrate scope of the

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• galvanostatic conditions at a platinum electrode in DMF containing 6% water with NaBr as a supporting electrolyte. A mixture of products was formed, among them “3,5,6-trihydroxycholesterol” (probably cholesta-3β,5ξ,6ξ-triol), 7-oxocholesterol (9), 5,6-epoxycholesterol (10), and 7-ketocholesterol were identified

• electrochemical process. However, in some cases, reasonable yields of products are obtained and these reaction conditions may be of interest in practice. Preferential sites of cholesterol electrooxidation. Functionalization of the cholesterol side chain. Oxidation of cholestane-3β,5α,6β-triol triacetate (3) with