Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• (trimethylsilanyl)diseleno[2,3-b:3′,2′-d]thiophene ((TMS)2-bb-DST), and 2,5-di(trimethylsilanyl)diseleno[2,3-b:3′,2′-d] selenophene ((TMS)2-bb-DSS) were used as starting materials to synthesize three S-shaped double helicenes (i.e., DH-1, DH-2, and DH-3) through monobromination, formylation, the Wittig reaction

• sulfur atoms on the same side is defined as bb by us. The double Wittig reaction of 4a and 4b with 1,3-phenyldimethyltriphenylphosphonium bromide afforded compounds 5a and 5b with yields of 46% and 64%, respectively. After the double Wittig reaction of 4c we obtained a mixture of cis and trans isomers of

New efficient synthesis of polysubstituted 3,4-dihydroquinazolines and 4H-3,1-benzothiazines through a Passerini/Staudinger/aza-Wittig/addition/nucleophilic substitution sequence

• Long Zhao,
• Mao-Lin Yang,
• Min Liu and
• Ming-Wu Ding

Beilstein J. Org. Chem. 2022, 18, 286–292, doi:10.3762/bjoc.18.32

• /addition/nucleophilic substitution reactions. Keywords: aza-Wittig reaction; 3,4-dihydroquinazoline; 4H-3,1-benzothiazine; nucleophilic substitution; Passerini reaction; Staudinger reaction; Introduction The chemistry of 3,4-dihydroquinazolines and 4H-3,1-benzothiazines is of constant interest owing to

• reaction has also been utilized widely in preparation of various heterocycles under mild neutral conditions [30][31][32]. Recently we have reported the synthesis of 3H-2-benzoxepin-1-ones, 4H-3,1-benzoxazines and oxazoles by combination of a Passerini with an intramolecular aza-Wittig reaction [33][34][35

• ]. Continuing our interest in the synthesis of N-heterocycles via the aza-Wittig reaction and multicomponent reactions [36][37][38], we wish to report herein a facile synthesis of polysubstituted 3,4-dihydroquinazolines and 4H-3,1-benzothiazines via sequential Passerini/Staudinger/aza-Wittig/addition

Synthesis and late stage modifications of Cyl derivatives

• Phil Servatius and
• Uli Kazmaier

Beilstein J. Org. Chem. 2022, 18, 174–181, doi:10.3762/bjoc.18.19

• NMR spectra. The solubility issues forced us to investigate also other modification protocols. Thus, macrocycle 11 was subjected to an ozonolysis with subsequent Wittig reaction in a one-pot manner (Scheme 4). Performing the ozonolysis in presence of pyridine led to immediate reduction of the primary

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

• liberated using TBAF to give compound 27 in 97% yield over two steps. The alcohol group in 27 was then oxidized to the corresponding aldehyde under Swern conditions and subsequently subjected to a Wittig reaction with a two-carbon phosphonium ylide reagent. The desired α,β-unsaturated ester 28 was then

• primary alcohol 99 (90%). Oxidation of this moiety with IBX to its corresponding aldehyde served as a substrate for the two-carbon homologation via Wittig reaction giving ester 96 in 80% yield over the two steps. After reduction of the ester group to its primary alcohol counterpart, the Sharpless

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• fourth and final step, phenoxydiphenylalkene derivative 4a was prepared by a Wittig reaction, which was carried out using methyltriphenylphosphonium bromide with ketone 3a, in basic medium, at room temperature, and dry THF. After the structures of the starting compounds were elucidated, the method

• synthesized by Grignard reaction of 1a–l and aryl(or alkyl)magnesium bromides. Then 3a–l were prepared by oxidation of 2a–l using PCC. The final alkene compounds 4a–l were obtained by Wittig reaction using Me(Ph)3PBr, t-BuOK, and NaH. All substrates were purified by crystallization or column chromatography

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• methodology, they synthesized 2,3,6,7-anthracenetetracarbonitrile (90) in a good yield (84%) by double intermolecular Wittig reaction of the protected benzenetetracarbaldehyde 87 with reagent 88, followed by deprotection and double ring-closing reaction of intermediate 89; they used a mixture of triflic acid

• /water in the first step and trimethylamine in the next reaction step [56]. Other procedures In 2008, Lin et al. reported a homo-elongation protocol to obtain acene diesters and dinitriles starting from dialdehydes (Scheme 23) [57]. This methodology was based on a Wittig reaction between substituted [n

• Wittig reaction affording naphthalenes 144. Isomerization of compounds 144 produced substituted styrenes 145. With the styrenes 145 in hands, the authors employed the Grubbs II catalyst-promoted ring closure to obtain the benzo[a]anthracenes 146a (85% yield) and 146b (43% yield) [67]. Other procedures In

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• Scheme 3 consisting of the following steps: (i) Wittig reaction of 2-bromobenzaldehyde with methyltriphenylphosphonium iodide ylide, (ii) lithiation of the resultant o-bromostyrene with n-BuLi and reaction of the aryl lithium species with ethylene oxide, and (iii) oxidation of the resultant primary

• -vinylphenyl)acetaldehyde (13a) using the route as outlined in Scheme 4. The synthesis started with the Wittig reaction of 2-bromobenzaldehyde (9a) with (methoxymethyl)triphenylphosphonium chloride (MTPPC) upon action with n-butyllithium in THF at 0 °C to give the vinyl ether 10a that was subjected to acidic

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• Wittig reaction with methylenetriphenylphosphorane (Ph3P=CH2) produced the 5′-methylene derivative [62]. Finally, oxidation with meta-chloroperbenzoic acid (mCPBA) afforded the nucleoside 97. Treatment of the nucleoside 97 with Grignard reagent PhMgBr in THF produced nucleoside 98, whose secondary

Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

• Takashi Nishiyama,
• Erina Hamada,
• Daishi Ishii,
• Yuuto Kihara,
• Nanase Choshi,
• Natsumi Nakanishi,
• Mari Murakami,
• Kimiko Taninaka,
• Noriyuki Hatae and
• Tominari Choshi

Beilstein J. Org. Chem. 2021, 17, 730–736, doi:10.3762/bjoc.17.62

• . Consequently, we decided to develop a new synthetic strategy for the preparation of trigonoine B (1). Carbodiimides are valuable synthetic intermediates that can be obtained by an aza-Wittig reaction of isocyanates with iminophosphoranes or by dehydration of urea [26]. Molina et al. previously reported the

• synthesis of 2-aminopyridine derivatives through an electrocyclization of conjugated carbodiimides derived from an aza-Wittig reaction of iminophosphoranes and isocyanates [27]. Hibino and co-workers also achieved the preparation of mutagenic amino-α-carbolines (2-amino-9H-pyrido[2,3-b]indole, AαC) and

• MeAαC by the electrocyclization of 3-alkenyl-2-carbodiimidoindole derivatives obtained by an aza-Wittig reaction of indol-2-yl-iminophosphoranes and isocyanates [28]. In this work, we report the first total synthesis of trigonoine B (1) involving the construction of a pyrrolo[2,3-c]quinoline framework

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

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

• , it was transformed into (E)-vinylboronate (+)-145b in perfect stereoselectivity by using the recently developed boron-Wittig reaction with bis[(pinacolato)boryl]methane (144) [79]. By applying the Corey–Fuchs dibromoolefination and followed by Pd-catalyzed hydrogenolysis under Uenishi's conditions

• [80], compound (Z)-(+)-143a delivered the bromodiene (Z,Z)-(+)-145a in good yield and stereoselectivity. Isomerization of (Z)-(+)-143a to (E)-(+)-143b was carried out successfully using sterically hindered base DBU or DABCO. Treatment of (E)-(+)-143b with 144 using the boron-Wittig reaction [79

3-Acetoxy-fatty acid isoprenyl esters from androconia of the ithomiine butterfly Ithomia salapia

• Florian Mann,
• Daiane Szczerbowski,
• Lisa de Silva,
• Melanie McClure,
• Marianne Elias and
• Stefan Schulz

Beilstein J. Org. Chem. 2020, 16, 2776–2787, doi:10.3762/bjoc.16.228

• ). A Wittig reaction with pentylphosphonium bromide resulted in bromoalkene 21 in a 9:1 Z/E-mixture. In the following step, the Grignard reagent of 21 was converted into the respective Gilman cuprate with Cu(I)I for the selective reaction with the epoxide function of (S)-22 [34]. The hydroxyester 23

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• relatively short list: the reduction of the OH group of the C(CF3)2OH moiety (this protocol was employed in the synthesis of enantiomerically pure (S)-5,5,5,5',5',5'-hexafluoroleucine [1]); the Wittig reaction of Ph3P=C(O)C(O)OR with hexafluoroacetone, followed by the hydrogenation of the CH=C(CF3)2 unit

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

• context, their journey started from syn-tris(oxonorborneno)benzene 23, obtained via palladium-catalyzed cyclotrimerization of iodonorbornene. The C3-symmetric compound 23 was then converted into the methylene groups containing compound 103 using Wittig reaction which on further treatment with

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

• Dalel El-Marrouki,
• Sabrina Touchet,
• Abderrahmen Abdelli,
• Hédi M’Rabet,
• Mohamed Lotfi Efrit and
• Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

• the target compounds required the prior preparation of a panel of variously substituted 1,4-diketones 5. The 1,4-diketones 5 have been prepared either by a Nef reaction [56] from the corresponding nitroenone 3 or a Wittig reaction [57] from 1,2-cyclohexanedione and the corresponding ylide 4 (Scheme 2

• route remains limited in terms of chemical diversity as it depends on the availability of the corresponding nitro derivative. It was thus decided to move on to the Wittig reaction [57], offering a much more straightforward and efficient route to a panel of new diketones, 5e–k, from 1,2-cyclohexanedione

• and the corresponding Wittig ylides 4a–g (readily accessible from the corresponding halogenated derivatives, Scheme 2). Indeed, the Wittig reaction leads exclusively to the isomerized products 5. With the 1,4-diketones 5 in hand, we first investigated the synthesis of indole and indolone derivatives

Facile synthesis of 7-alkyl-1,2,3,4-tetrahydro-1,8-naphthyridines as arginine mimetics using a Horner–Wadsworth–Emmons-based approach

• Rhys A. Lippa,
• John A. Murphy and
• Tim N. Barrett

Beilstein J. Org. Chem. 2020, 16, 1617–1626, doi:10.3762/bjoc.16.134

• , GlaxoSmithKline disclosed a route to a fluoropyrrolidine 6 using a Wittig reaction between phosphonium salt 4 and aldehyde 5 [2]. The synthesis of phosphonium salt 4 (itself requiring 6 steps including partial saturation of a 1,8-naphthyridine moiety) and the formation of the triphenylphosphine oxide byproduct in

• integrin inhibitors. Commonly used synthetic routes to tetrahydro-1,8-naphthyridine moieties by hydrogenation of saturated naphthyridines 3. Previous synthetic route to fluoropyrrolidine 6 utilising a Wittig reaction and the novel, higher yielding route using a Horner–Wadsworth–Emmons reaction. Synthesis

A simple and easy to perform synthetic route to functionalized thienyl bicyclo[3.2.1]octadienes

• Dragana Vuk,
• Irena Škorić,
• Valentina Milašinović,
• Krešimir Molčanov and
• Željko Marinić

Beilstein J. Org. Chem. 2020, 16, 1092–1099, doi:10.3762/bjoc.16.96

• [3.2.1]octadiene compound with an extended conjugation. Keywords: bicyclo[3.2.1]octadiene; photocyclization; thiophene; Vilsmeier–Haack reaction; Wittig reaction; Introduction The bicyclo[3.2.1]octane skeleton has become the subject of intensive research in recent years [1][2][3]. Its presence in

• purification, the aldehydes 1 and 2 were obtained in very good yields (1: 79%; 2: 68%), and subsequently used as novel starting substrates for further addition/condensation reactions. The Wittig reaction of the prepared aldehydes with the corresponding triphenylphosphonium salts provided five new styryl

Design and synthesis of diazine-based panobinostat analogues for HDAC8 inhibition

• Sivaraman Balasubramaniam,
• Sajith Vijayan,
• Liam V. Goldman,
• Xavier A. May,
• Kyra Dodson,
• Sweta Adhikari,
• Fatima Rivas,
• Davita L. Watkins and
• Shana V. Stoddard

Beilstein J. Org. Chem. 2020, 16, 628–637, doi:10.3762/bjoc.16.59

• obstacle was overcome by using a modified Fieser work-up procedure to yield the aldehyde 6 in high yield, 78%. Then, aldehyde 6 was converted to the α,β-unsaturated trans-ester 7 through a Wittig reaction with the phosphorane synthon 8, which was derived from ethyl bromoacetate at 60 °C for 8 h in THF in

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

• synthesis of compound 15 from ʟ-dimethyl tartrate and butanone was 32%. We initially attempted to carry out the Wittig reaction of compound 15 with n-pentyltriphenylphosphonium bromide and the conditions of the individual reactions are collected in Table 1. Product 16 was obtained with various yields

• then used in the synthesis of (+)-disparlure (1), (−)-disparlure (3), (+)-monachalure (2), and (−)-monachalure (4). First, the (+)-enantiomers 1 and 2 were synthesized (Scheme 4). In a Wittig reaction with n-nonyltriphenylphosphonium bromide followed by reduction of the double bond, the longer chain of

• of the Wittig reaction. Supporting Information Supporting Information File 239: Experimental procedures of the synthesized compounds. Supporting Information File 240: Copies of 1H NMR and 13C NMR spectra. Acknowledgements We thank Dr Marietta Białoń for performing the GC–MS analysis. Funding A.D

Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C–F···H–C bonds

• Vuyisa Mzozoyana,
• Fanie R. van Heerden and
• Craig Grimmer

Beilstein J. Org. Chem. 2020, 16, 190–199, doi:10.3762/bjoc.16.22

• cross-coupling reaction [17], Negishi cross-coupling reaction [18] and Wittig reaction [17]. The concept of the incorporation of fluorine into organic molecules has gained much interest since Fried and Sabo reported the improvement of the therapeutic index of cortisol by the incorporation of a fluorine

Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose

• Lukáš Kerner and
• Paul Kosma

Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2

• antimicrobial drugs. C-glycosidically-linked phospholipid derivatives of 4-amino-4-deoxy-ʟ-arabinose have been prepared as hydrolytically stable and chain-shortened analogues of the native undecaprenyl donor. The C-phosphonate unit was installed via a Wittig reaction of benzyl-protected 1,5-arabinonic acid

• ). Conversion of benzylated reducing sugars, such as glucose [15], N-acetyl-ᴅ-glucosamine [16], and galactose [17], into the corresponding C-glycosyl phosponates using a Wittig reaction with methylenetriphenylphosphorane furnished the respective glycoenitols, which were then subjected to mercuriocyclization

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

Synthesis and biological evaluation of truncated derivatives of abyssomicin C as antibacterial agents

• Leticia Monjas,
• Peter Fodran,
• Johanna Kollback,
• Carlo Cassani,
• Thomas Olsson,
• Maja Genheden,
• D. G. Joakim Larsson and
• Carl-Johan Wallentin

Beilstein J. Org. Chem. 2019, 15, 1468–1474, doi:10.3762/bjoc.15.147

• the corresponding α-bromo esters 16 and 17, in 68% and 72% yield, respectively. Finally, intramolecular Wittig reaction of 16 or 17 in the presence of N,N-diisopropylethylamine and triphenylphosphine provided building blocks 4 and 5 in 75% and 77% yield (43% and 51% overall yields from

Introduction of an isoxazoline unit to the β-position of porphyrin via regioselective 1,3-dipolar cycloaddition reaction

• Xiujun Liu,
• Xiang Ma and
• Yaqing Feng

Beilstein J. Org. Chem. 2019, 15, 1434–1440, doi:10.3762/bjoc.15.143

• and Discussion The synthetic route to the β-isoxazoline-substituted porphyrin is depicted in Scheme 1, in which the double bond was furnished by Wittig reaction, followed by 1,3-dipolar cycloaddition reaction with stable dipoles. In detail, tetraphenylporphyrin (TPP) was used as starting material. A

• the β-position, a Wittig reaction was performed, in which the porphyrin phosphonium salt 1 reacted with 4-MeCO2-benzaldehyde in the presence of DBU to furnish the double bond, followed by insertion of Zn ions into the porphyrin cavity to give compound 2. Nitrile oxides [45] as one of the most reactive

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

• Ruben Pomar Fuentespina,
• José Angel Garcia de la Cruz,
• Gabriel Durin,
• Victor Mamane,
• Jean-Marc Weibel and
• Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

• -enynes through lithiation, borylation and rearrangement of cis or trans-alkynyloxiranes. This cascade reaction is stereospecific, probably due to the stereocontrolled group transfer from boron to the adjacent oxiranyl carbon in an oxiranylborate complex intermediate, followed by an internal bora-Wittig

• reaction. This method is particularly appealing, providing with good to high yields a wide diversity of functionalized E or Z tri- or tetrasubstituted α-enynes. Stereospecific formation of α-enynes from alkynyloxiranes. Trapping experiments of the oxiranyllithium derived from cis or trans-alkynyloxiranes

An efficient synthesis of the guaiane sesquiterpene (−)-isoguaiene by domino metathesis

• Yuzhou Wang,
• Ahmed F. Darweesh,
• Patrick Zimdars and
• Peter Metz

Beilstein J. Org. Chem. 2019, 15, 858–862, doi:10.3762/bjoc.15.83

• of the aldehyde function as the dimethyl acetal [16][17][18], hydroboration and oxidative work-up of 10 provided a mixture of epimeric alcohols 11 that was unified by Ley–Griffith oxidation [19] to give ketone 12 [20]. Subsequent Wittig reaction with ylide 13 and acetal cleavage of the resultant