Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

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

• elimination byproducts under DCC–DMAP-promoted acylation conditions, a two-step procedure for the acylation of 3’-OH group was applied. Acylation with the (R)-3-(p-methoxy)benzyloxytetradecanoic acid was initially performed to provide 6, the (p-methoxy)benzyl ether was removed with DDQ and the liberated OH

• . gingivalis lipid A 51. For the synthesis of pentaacyl lipid A 53, the 3’-O-p-methoxybenzyl group in 50 was cleaved by treatment with DDQ, and the liberated hydroxyl group was reacted with branched β-benzyloxy fatty acid to furnish fully acylated precursor 52. After the cleavage of the 1-O-allyl group, the

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

• -workers reported the synthesis of trifluoromethylated coumarin 71 and flavone 72 with CF3SO2Na (2 equiv), the hypervalent iodine F5-PIFA (pentafluorophenyliodine bis(trifluoroacetate)) (2 equiv) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 0.6 equiv). The trifluoromethylated compounds were obtained

• the direct trifluoromethylation of a wide variety of arenes and heteroarenes under visible-light irradiation [73]. The substrate scope was evaluated on 30 arenes and heteroarenes using 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as photocatalyst and CF3SO2Na as the CF3 radical source. The reaction

Preparation and isolation of isobenzofuran

• Morten K. Peters and
• Rainer Herges

Beilstein J. Org. Chem. 2017, 13, 2659–2662, doi:10.3762/bjoc.13.263

• ) and methylated to DMIBF (7) [8]. However, yields in our hands are quite low. It is known that benzyl ethers are prone to oxidative functionalization [20]. 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been used to selectively oxidize benzyl ethers to acetals in the presence of alcohols [21

• ]. Following a procedure of Doyle et al. we reacted commercially available phthalan (8) with DDQ and methanol in dry dichloromethane under a nitrogen atmosphere at room temperature, and obtained DMIBF (7) with a yield of 85% (Scheme 2) [22]. DMIBF (7) was treated with freshly prepared lithium diisopropylamide

• -Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 5.00 g, 22.0 mmol), dry dichloromethane (100 mL), methanol (900 μL, 22.2 mmol) and phthalan (8, 2.00 g, 16.7 mmol) were dissolved under a nitrogen atmosphere. The reaction mixture was stirred for 13 h at room temperature. The reaction was quenched with aq sodium

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P^® activation of 3-arylpropiolic acids

• Melanie Denißen,
• Alexander Kraus,
• Guido J. Reiss and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231

• use of phenylpropiolic acid chloride and phenylpropiolic acid as starting materials [45], and as well oxidative arene–alkyne cyclization with dichloro-5,6-dicyano-benzoquinone (DDQ) [46]. Based upon our experience in using propylphosphonic acid anhydride (T3P®) [47] as a condensation agent for in situ

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2017, 13, 2028–2048, doi:10.3762/bjoc.13.201

• by Ito and Ogawa who implemented DDQ-mediated oxidative transformation of the p-methoxybenzyl (PMB) protecting group at the C-2 position of the donor into a tethering mixed acetal with a hydroxy group of the acceptor [94]. The early studies have successfully applied this PMB-based IAD method to the

• stereoselectivity. Thus, mixed acetal 76 can be readily formed in 2 h by the addition of DDQ to a mixture of donor 74 and acceptor 75. Without further purification, the latter mixture can be glycosylated in the presence of MeOTf and DTBMP followed by acetylation to give disaccharide 77 in an excellent yield of 90

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

•  11) using 2,3-dichloro-5,6-dicyanoquinone (DDQ) as an efficient oxidant [67]. Su and co-workers have also reported an asymmetric version of the CDC reaction between terminal alkynes and sp3 C–H bonds under high speed ball milling conditions [68]. Several optically active 1-alkynyl

• tetrahydroisoquinoline derivatives were synthesized using a pyridine-based chiral ligand (PyBox, Scheme 12) in the presence of DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The coupling products were isolated in fair yields with ee’s (enantiomeric excesses) up to 79%. The milling copper balls were also identified as

• reacting catalyst. Su and co-workers reported an Fe(III)-catalyzed coupling of 3-benzyl indoles with molecules having active methylene group under solvent-free ball-mill in presence of silica gel as milling auxiliary. Using 10 mol % Fe(NO3)3·9H2O as catalyst and 1.0 equiv of DDQ afforded good yield of

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• -dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), KMnO4, transition metal-based oxidants and air have been extensively used to promote this transformation. o-Iodoxybenzoic acid (IBX)-mediated oxidative dehydrogenation IBX was first introduced as an oxidant (in oxidative dehydrogenation) by Nicolaou and co

• were facilitated by iodine and DDQ-mediated oxidative dehydrogenation as depicted in Scheme 6 [37][38][39][40]. Typically, quinazolinone 25 was refluxed in the polar solvent ethanol with iodine to afford the dihydro derivative 26 (Scheme 6). Interestingly, DDQ facilitated similar reactions at room

• temperature. DDQ also induced oxidative dehydrogenation in 2-thiazolidines 27 and 2-oxazolidines 28 at room temperature in the presence of 4 Å molecular sieves with dichloromethane as solvent to generate diversely substituted 2-thiazoles 29 and 2-oxazoles 30 (Scheme 7) [41]. The putative mechanism initiated

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

Total synthesis of elansolids B1 and B2

• Liang-Liang Wang and
• Andreas Kirschning

Beilstein J. Org. Chem. 2017, 13, 1280–1287, doi:10.3762/bjoc.13.124

• iodide 17 after O-acylation, iodination of the terminal alkyne and finally diimide-mediated syn-reduction [11]. Next, DDQ-mediated removal of the PMB protecting group yielded vinyl iodide 18. The synthesis of both fragments 13 and 18 set the stage for the Suzuki–Miyaura coupling which delivered the

• , 695.1837. Synthesis of vinyl iodide 18 DDQ (56.5 mg, 0.25 mmol, 3.0 equiv) was added to a stirred solution of 17 (55.8 mg, 0.083 mmol, 1.0 equiv) in CH2Cl2 (4.5 mL)/pH 7.0 phosphate buffer (0.45 mL) at 0 °C. After stirring for 1.5 h, the reaction mixture was terminated by addition of a saturated, aqueous

Total syntheses of the archazolids: an emerging class of novel anticancer drugs

• Stephan Scheeff and
• Dirk Menche

Beilstein J. Org. Chem. 2017, 13, 1085–1098, doi:10.3762/bjoc.13.108

• protection of the free alcohol and deprotection of the primary PMB-protected alcohol with DDQ, the resulting alcohol was oxidized to the corresponding aldehyde. The crude aldehyde was then directly transformed into the (Z)-α,β-unsaturated ester 62 as a single stereoisomer by a Still–Gennari [72] olefination

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

• , 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

• -hydroxy group in 14 followed by treatment with DDQ could yield the desired 5-hydroxy product in high yield. Indeed, acetylation of alcohol 14 with acetic anhydride delivered ester 15 in 91% yield. Removal of the PMB group in 15 with DDQ resulted in a very clean reaction, affording alcohol 16 in an

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

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

• reducing to the non-reducing end (Scheme 8). Union of 4 and 5 (Scheme 7) produced disaccharide 41 as the key intermediate, the naphthyl protecting group of which was cleaved in 70% yield using DDQ [37] to afford 42. Thioglycoside 43 failed to react with disaccharide 42 to furnish the desired trisaccharide

• activator proceeded to produce trisaccharide 44 in 65% yield. Removal of the C2 naphthyl ether using DDQ provided acceptor 45, which in turn was reacted with glucosyl thioglycoside 7 in the presence of NIS and TfOH to produce α-linked tetrasaccharide 46 in 62% yield (Scheme 8). At this stage, the 2

• protected hexasaccharide 51. Reagents and conditions: (a) DDQ, CH2Cl2/MeOH (9:1), rt, 70%; (b) 43, NIS, TfOH, CH2Cl2, −20 °C (no reaction) or 6, TMSOTf, Et2O/CH2Cl2 (4:1), −20 °C (65%); (c) DDQ, CH2Cl2/MeOH (9:1), rt, 55%; (d) 7, TMSOTf, Et2O/CH2Cl2 (4:1), −20 °C, 62%; (e) NaOMe (0.5 M in MeOH), THF/MeOH (1

Copper-catalyzed asymmetric sp³ C–H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst

• Pierre Querard,
• Inna Perepichka,
• Eli Zysman-Colman and
• Chao-Jun Li

Beilstein J. Org. Chem. 2016, 12, 2636–2643, doi:10.3762/bjoc.12.260

• of THIQs with arylboronic esters via asymmetric organocatalysis methodology [25][28]. The use of chiral tartaric acid derivatives, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and high temperature (70 °C) were found to be the optimal conditions to obtain the desired arylated product with

Total synthesis of leopolic acid A, a natural 2,3-pyrrolidinedione with antimicrobial activity

• Atul A. Dhavan,
• Rahul D. Kaduskar,
• Loana Musso,
• Leonardo Scaglioni,
• Piera Anna Martino and
• Sabrina Dallavalle

Beilstein J. Org. Chem. 2016, 12, 1624–1628, doi:10.3762/bjoc.12.159

• cleavage with cerium ammonium nitrate (CAN) or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). Thus, 2,3-pyrrolidinedione 3 was obtained by the reaction of ethyl acrylate with p-methoxybenzylamine, followed by treatment with diethyl oxalate (Scheme 1) [12]. On the basis of NMR data, the compound exists as an

• DIBAL-H gave the corresponding primary alcohol, which was converted into bromide 5 by Appel reaction with PPh3 and CBr4. The phosphonium salt obtained from this bromide was subjected to a Wittig reaction with nonanal, to afford compound 6 [12]. Attempts to remove the PMB protecting group (CAN, DDQ, TFA

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

• bromide (56), we envisaged its subsequent deprotonation and addition to chloroacetone would afford (E)-1-((2-methyl-4-chlorobut-2-enyloxy)methyl)-4-methoxybenzene (57). Inclusion of the PMB-ether was beneficial due to the ease with which it can be cleaved using readily available reagents, e.g., DDQ or CAN

• -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

• the moderate yield was not problematic as rac-68 and rac-69 were readily separable, allowing rac-68 to be recycled (based on recovered starting material the yield was almost quantitative). Oxidative O-PMB deprotection of rac-69 using DDQ in biphasic dichloromethane/water generated 1° alcohol (±)-2

Indenopyrans – synthesis and photoluminescence properties

• Andreea Petronela Diac,
• Ana-Maria Ţepeş,
• Albert Soran,
• Ion Grosu,
• Anamaria Terec,
• Jean Roncali and
• Elena Bogdan

Beilstein J. Org. Chem. 2016, 12, 825–834, doi:10.3762/bjoc.12.81

• -benzoquinone (DDQ), led to indeno-α-pyrones 4–6 (Scheme 2), in not very satisfying yields. Investigations carried out for the dehydrogenation reaction of the isomeric mixture 2'a/3''a (Scheme 2) revealed the formation of the α-pyrone 6a (15% yield), which was the oxidation product of isomer 3''a. In the same

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

• Bu4NBr resulted in bromohydrine 47, followed by levulinyl (Lev) protection of the hydroxy group (product 48). Nucleophilic substitution at the 6'-position with Bu4NN3 gave the naturally occurring (5'S,6'S)-stereochemistry of the uridine core structure in a double inversion manner [78][99]. DDQ oxidation

A selective and mild glycosylation method of natural phenolic alcohols

• Mária Mastihubová and
• Monika Poláková

Beilstein J. Org. Chem. 2016, 12, 524–530, doi:10.3762/bjoc.12.51

• by the reduction of the corresponding acetylated aldehydes or acids. Various stereoselective 1,2-trans-O-glycosylation methods were studied, including the DDQ–iodine or ZnO–ZnCl2 catalyst combination. Among them, ZnO–iodine has been identified as a new glycosylation promoter and successfully applied

• performed in the presence of known mild catalysts such as Ag2O [33] (method A), the less frequently used ZnO–ZnCl2 system [34] (method B) and the combination of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) with iodine (DDQ–I2) [35] (method C). In addition ZnO–I2 (method D) was successfully applied as a

• reactions in DCM promoted by Ag2O (Table 1, entry 1, 57%) and ZnO–I2 (Table 1, entry 4, 56%) gave comparably good yields. DDQ–I2 in ACN (Table 1, entry 3, 68%) gave 21b in the highest yield, in addition to the exclusive selectivity and the shortest reaction time (Table 1, entry 5). Therefore this promoter

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

• –Schuster products could also be observed, but in small amounts and not as pure compounds. It is worth mentioning that treatment of 22 with DDQ led to removal of the DMB group, affording the major product 27 (23%) exhibiting a keto group in the benzylic indole position (Scheme 4). This transformation might

Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems

• Kirk W. Shimkin and
• Donald A. Watson

Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248

• dihydrofurans could be easily converted into furans using DDQ in a one-pot process. In addition to α-bromo esters and ketones, Lei and co-workers have also recently shown that benzylic halides could undergo radical alkenylation via copper catalysis [39]. By exploiting the propensity of benzyl halides to form

Easy access to heterobimetallic complexes for medical imaging applications via microwave-enhanced cycloaddition

• Nicolas Desbois,
• Sandrine Pacquelet,
• Adrien Dubois,
• Clément Michelin and
• Claude P. Gros

Beilstein J. Org. Chem. 2015, 11, 2202–2208, doi:10.3762/bjoc.11.239

• trifluoroacetic acid, followed by oxidation under the action of DDQ. Cu and Ga complexes were prepared by the strategy outlined in Scheme 2. The insertion of Cu into corrole 1 was easily achieved with Cu(OAc)2·H2O in THF during 15 min. To obtain the gallium corrole 8b, free-base azidocorrole 1 was dissolved in a

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• required RRM product 208 was formed in 26% yield. Later, the expected chiral buckybowl 209 was assembled via aromatization of 208 in the presence of DDQ (Scheme 42). Design of intricate polyquinanes has been considered as a challenging task for synthetic chemists. To this end, Fallis and co-workers [46

Structure and conformational analysis of spiroketals from 6-O-methyl-9(E)-hydroxyiminoerythronolide A

• Ana Čikoš,
• Irena Ćaleta,
• Dinko Žiher,
• Mark B. Vine,
• Ivaylo J. Elenkov,
• Marko Dukši,
• Dubravka Gembarovski,
• Marina Ilijaš,
• Snježana Dragojević,
• Ivica Malnar and
• Sulejman Alihodžić

Beilstein J. Org. Chem. 2015, 11, 1447–1457, doi:10.3762/bjoc.11.157

• 3: 1H NMR (600 MHz, CDCl3) δ 0.85 (d, J = 7.3 Hz, 3H, 8-Me), 0.87 ( t, J = 7.3 Hz, 3H,15-H), 1.10 (s, 3H, 6-Me), 1.23 (d, J = 7.5 Hz, 3H, 4-Me), 1.27 (s, 3H, 12-Me), 1.32 (d, J = 7.2 Hz, 3H, 2-Me), 1.35 (ddq, J = 14.0, 11.9, 7.3 Hz, 1H, 14-H), 1.46 (dd, J = 14.1 Hz, 1H, 7-H), 1.66 (dqd, J = 14.0

• , 3H, 6-Me), 1.42 (ddq, J = 14.0, 11.0, 7.3 Hz, 1H, 14-H), 1.61 (dd, J = 12.4, 4.0 Hz, 1H, 7-H), 1.68 (dqd, J = 14.0, 7.3, 2.4 Hz, 1H, 14-H), 1.67–1.72 (m, 1H, 7-H), 1.72 (d, J = 1.6 Hz, 3H, 10-Me), 1.87 (dqd, J = 13.3, 6.7, 4.2 Hz, 1H, 8-H), 2.31 (q, J = 7.1 Hz, 1H, 4-H), 2.89 (dq, J = 7.5 Hz, 1H, 2-H

• ), 1.18 (s, 3H, 12-Me), 1.33 (s, 3H, 6-Me), 1.35 (ddq, J = 14.5, 11.3, 7.2 Hz, 1H, 14-H), 1.50 (dd, J = 12.7 Hz, 1H, 7-H), 1.62 (dd, J = 12.0, 3.7 Hz, 1H, 7-H), 1.67 (dqd, J = 14.0, 7.5, 2.4 Hz, 1H, 14-H), 1.66 (d, J = 1.6 Hz, 3H, 10-Me), 1.86 (dqd, J = 13.4, 6.6, 3.8 Hz, 1H, 8-H), 2.18 (qdd, J = 7.8, 3.0

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142