Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• . In most cases, the C2–C3 bond was formed by Ireland-, Johnson-, or Eschenmoser–Claisen rearrangement [10][11][12][13][14][15][16][17]. Alternatively, Evans methodology has been used [18][19][20]. The central C4–C5 double bond has also been constructed by Wittig reaction, cross metathesis, and ring

Synthesis of 1,2-divinylcyclopropanes by metal-catalyzed cyclopropanation of 1,3-dienes with cyclopropenes as vinyl carbene precursors

• Jesús González,
• Alba de la Fuente,
• María J. González,
• Laura Díez de Tejada,
• Luis A. López and
• Rubén Vicente

Beilstein J. Org. Chem. 2019, 15, 285–290, doi:10.3762/bjoc.15.25

• cyclopropanes contrasts with the existence of few straightforward routes for their syntheses. Typical methods rely on the use of reagents containing the required cyclopropane ring, which involve multistep sequences for the installation of adequate functionalization. Thus, Wittig-type olefination with

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• aldehyde (S)-18 prepared from O-benzyl-L-serine in three standard steps [53] was elongated by a two-carbon fragment employing a Wittig reaction to give Z-alkene 19. To introduce the next center of chirality of the required configuration a iodocyclocarbamation reaction was applied to give trans-oxazolidin-2

• a protected serinal (R)-23 [54]. Wittig olefination extended the alkyl chain by two carbon atoms and simultaneously installed the C=C bond which was subjected to the intramolecular epoxidation to give a >20:1 mixture of aminoepoxides with the isomer (2S,3R,4R)-117 dominating. Without isolation this

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• exclusive trans regularity and contained vinyl groups at the both polymer chain ends. These groups were treated with a Mo catalyst to generate the corresponding Mo-alkylidene moieties followed by the Wittig-type cleavage with various aldehydes, gave an opportunity to utilize atom transfer radical

• subsequent Wittig coupling (Scheme 4) [64]. The ADMET technique was used not only for the synthesis of polymer telechelics but also for their assembling into multiblock copolymers. A simple one-pot way for the preparation of random multiblock copolymers was proposed in reference [65]. A mixture of

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

• Christiane Schultze and
• Bernd Schmidt

Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278

• Christiane Schultze Bernd Schmidt Universität Potsdam, Institut fuer Chemie, Karl-Liebknecht-Straße 24–25, D-14476 Potsdam-Golm, Germany 10.3762/bjoc.14.278 Abstract 8-Allylcoumarins are conveniently accessible through a microwave-promoted tandem Claisen rearrangement/Wittig olefination

• the past few years. Starting materials are allyl ethers of salicylic aldehydes or ketones 5 and the stable ylide ethyl (triphosphoranylidene)acetate (6), which upon microwave irradiation undergo a tandem Claisen rearrangement/Wittig olefination/cyclization sequence. This sequence was pioneered by the

• groups of Harwood [31][32] and Mali [33][34][35][36], and its Wittig olefination/cyclization part has been employed in the synthesis of various coumarins without alkyl substituents at position 8 [37][38][39]. In all previous reports conventional heating was used to induce the tandem sequence. In this

Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step

• Pierre-Antoine Nocquet,
• Aurélie Macé,
• Frédéric Legros,
• Jacques Lebreton,
• Gilles Dujardin,
• Sylvain Collet,
• Arnaud Martel,
• Bertrand Carboni and
• François Carreaux

Beilstein J. Org. Chem. 2018, 14, 2949–2955, doi:10.3762/bjoc.14.274

• obtained for the desired products due to the formation of substantial amounts of ring-opened byproducts 10 resulting from the hydride addition to the carbonyl group of the oxazolidinone ring [33][34]. The alcohols 9 were then subjected to a Swern oxidation followed by a Wittig reaction to generate the

Domino ring-opening–ring-closing enyne metathesis vs enyne metathesis of norbornene derivatives with alkynyl side chains. Construction of condensed polycarbocycles

• Ritabrata Datta and
• Subrata Ghosh

Beilstein J. Org. Chem. 2018, 14, 2708–2714, doi:10.3762/bjoc.14.248

• ring-opened product 18 using an alternative path. The double bond in the norbornene nucleus in compound 17 was cleaved in the traditional way by treatment with OsO4/NaIO4 and the resulting dialdehyde on Wittig reaction provided the diene 18 in 66% yield in two steps. Amazingly when compound 18 was

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• generated the cross-coupling product 22 (72%). Next, aldehyde 22 was subjected to Wittig olefination to provide the corresponding alkene 23 (69%), which on subsequent treatment with KOt-Bu in THF gave the isomerized product 24 (73%). Later, RCM of isomerized olefin 24 with the help of G-II catalyst offered

• end, aldehydes 58a,b were subjected to a Wittig olefination followed by condensation with acryloyl chloride (60) to generate the corresponding diolefinic substrates such as 61a (70%) and 61b (65%). Later, these diolefins 61a,b were subjected to RCM with the aid of G-II catalyst 2 to furnish the

Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

• Pamarthi Gangadhar,
• Sayini Ramakrishna,
• Ponneri Venkateswarlu and
• Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

• reaction steps. A common aldehyde intermediate has been used for the synthesis of both strongylodiols. Keywords: alkylation; Cadiot–Chodkiewicz coupling; Corey–Bakshi–Shibata reduction; Mosher’s analysis; Wittig reaction; Introduction Diacetylenic polyol compounds [1][2] originated from marine sources

• strongylodiol I The retrosynthetic analysis for strongylodiols H and I is delineated in Scheme 1. We envisaged that the target molecules strongylodiol H (9) and strongylodiol I (10) can be synthesized by a Wittig reaction of a common intermediate aldehyde 14 with triphenylphosphonium Wittig salts 15 and 16

• to Wittig olefination reaction with triphenylphosphonium salt of n-nonyl bromide 15 in presence of n-BuLi to produce the corresponding Z-olefin 28 exclusively in 83% yield. Di-desilylation of compound 28 was easily achieved with n-tetrabutylammonium fluoride to furnish the target molecule

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

• presence of the hydroxy functional group acting as a transition-state analog. The synthesis of the inhibitors commenced with the conversion of aldehyde 127 into alkene 128 via a Wittig reaction followed by epoxidation to furnish epoxide 129. Regioselective opening of the epoxide ring with a thiolate gave

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• by manipulations of 5. After acetal hydrolysis and the subsequent hydride reduction, 4-thioarabinose derivative 9 was obtained in good yield. Introduction of a TBDPS group at the primary hydroxy group of 9, oxidation and Wittig reaction, followed by deprotection of the benzyl group, gave allyl

Oligonucleotide analogues with cationic backbone linkages

• Melissa Meng and
• Christian Ducho

Beilstein J. Org. Chem. 2018, 14, 1293–1308, doi:10.3762/bjoc.14.111

• route using Wittig–Horner olefination and catalytic asymmetric hydrogenation as key steps (reactions not shown) [86][87][90][91][92]. Using 'dimeric' building blocks (S)-49, (R)-49, (S)-50, and (R)-50 (Scheme 5), automated DNA synthesis under standard conditions enabled the preparation of partially

• peptide synthesis using the monomeric 3'-amino-nucleosyl amino acids (S)-56 and (R)-56, respectively, as building blocks. The synthesis of thymidinyl amino acids 56 was again started from a corresponding 5'-aldehyde 57 using Wittig–Horner olefination and catalytic asymmetric hydrogenation as key steps

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• -benzosesquifulvalene 55 via condensation of 1,2,3,4-tetrachlorocyclopentadiene and 4,5-benzotropone (11) [64]. The thia-heptafulvalene 56 was synthesized by Wittig–Horner reaction of 4,5-benzotropone (11) with 2-diethoxyphosphinyl-1,3-benzodithiole [59]. The reactants used for the synthesis of benzoheptafulvalene

Recent advances in synthetic approaches for medicinal chemistry of C-nucleosides

• Kartik Temburnikar and
• Katherine L. Seley-Radtke

Beilstein J. Org. Chem. 2018, 14, 772–785, doi:10.3762/bjoc.14.65

• (compound 23) is shown in Figure 9, which involves installing an allyl group at C1' (20) and converting the C2'–CN to an aldehyde (21) followed by a Wittig reaction to install a second allyl group at C2' (22). Second generation Grubb’s catalyst was used for the ring formation, followed by hydrogenation to

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• used in liquid-assisted grinding (LAG) and properly chosen counter-ion pairing increases the percentage conversion of stilbenes in a mechanochemical Wittig reaction. Utilizing stepwise addition/evaporation of ethanol in liquid-assisted grinding also allows for the tuning of the diastereoselectivity in

• the Wittig reaction. Keywords: green chemistry; high-speed ball milling; HSBM; LAG; liquid-assisted grinding; Wittig; Introduction Mechanochemistry is maturing as a discipline and continuing to develop and grow [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Thus it is important to continue

• of the Wittig reaction under mechanochemical conditions [17][18]. The Wittig reaction is one of the most useful reactions for the synthesis of olefins [19][20][21][22][23]. Aside from its synthetic utility, its unique reaction mechanism (shown in Figure 1) and inherent diastereoselectivity has led to

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• attention is paid to the use of these compounds as building blocks for the synthesis of carbo- and heterocyclic systems after their prior transformation into the corresponding phosphorus ylides, followed by the intramolecular Wittig reaction with various types of nucleophiles containing a carbonyl function

• in their structures. Keywords: 2-aminovinylphosphonium salts; nucleophilic addition; phosphorus ylides; vinylphosphonium salts; Wittig reaction; Introduction Vinylphosphonium salts have been known for a long time, although significant interest in these compounds dates back to 1964, when Schweizer

• to vinylphosphonium salt. A phosphorus ylide thus generated undergoes a subsequent intramolecular Wittig reaction, leading to a carbo- or heterocyclic ring closure (Scheme 2) [1][2][3]. This reaction can be considered as a general method for the synthesis of carbo- and heterocyclic systems

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

• -heterocyclic carbenes (NHCs, Scheme 11) [40]. The reaction was first performed on the γ,γ-difluoro-α,β-enal 52 which was synthesized via a Wittig olefination of 50. The resulting monofluoroalkene Boc-Val-ψ[(Z)-CF=CH]-Gly-OEt was obtained in good yield. Afterwards, the γ,γ-difluoro-α,β-enoylsilane 55, obtained

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

• ]. Therefore we turned our attention to converting the fluorinated aldehyde 8b (Scheme 1) into the allylic fluoride 16. The crude fluorinated aldehyde 8b was treated with a variety of olefination reagents (e.g., Tebbe; Wittig; reagent 15 [27]). Unfortunately, however, the desired allylic fluoride 16 was either

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• intermediate 45, which was subjected to Wittig olefination. Subsequent aza-Sakurai cyclization of intermediate 46 provided tricyclic derivative 47 as a single stereoisomer, which was then transformed into target myrioneurinol by standard operations. Addition of organometallic reagents to conjugated

Synthesis of 2-aminosuberic acid derivatives as components of some histone deacetylase inhibiting cyclic tetrapeptides

• Shital Kumar Chattopadhyay,
• Suman Sil and
• Jyoti Prasad Mukherjee

Beilstein J. Org. Chem. 2017, 13, 2153–2156, doi:10.3762/bjoc.13.214

• conventional steps viz. HWE-type olefination leading to the unsaturated ester 5, saturation of the double bond in the latter to 6, reduction of the ester moiety in 6 to the alcohol 7 followed by its oxidation. The aldehyde 8 thus obtained was subjected to a Wittig olefination to obtain the desired alkene 9 in

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

• ) compared to the conventional method that generally takes days to a week for completion. The reaction of methyl acrylate with different para-substituted aryl aldehydes in the presence of 20 mol % 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyst at 0.5–45 h yielded the MBH products in 28–98% yield [53]. Wittig

• -free Wittig reaction of organic halides with aldehydes or ketones (Scheme 6) [55]. Suzuki Coupling In 2000, Peters and co-workers first reported the palladium-catalyzed Suzuki coupling reaction under ball-milling conditions [56]. In a planetary mill for 30–60 min, the mixture of aryl halide (1.0 equiv

• -(S)-proline derived catalyst [49]. b) Report using α,α-dipeptide-based catalyst [50]. Mechanochemical Michael reaction [51]. Mechanochemical organocatalytic asymmetric Michael reaction [52]. Mechanochemical Morita–Baylis–Hillman (MBH) reaction [53]. Mechanochemical Wittig reactions [55

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

• Carolina S. García,
• Paula M. Uberman and
• Sandra E. Martín

Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166

• Wittig reaction followed by different metal-catalyzed reactions and harsh conditions are usually required [60][61][62]. In our case, the desired product was obtained under environmentally friendly reaction conditions and in a short reaction time. Thus, the PVP-Pd NPs proved to be an effective catalyst to

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

• Wittig, HWE or Julia olefination with the respective C15–C20 fragments. The most extensive contributions to the synthesis of mycolactones have come from Kishi and co-workers, who pioneered the synthesis of the extended mycolactone core structure. The group’s approaches to this problem have evolved over

A practical and efficient approach to imidazo[1,2-a]pyridine-fused isoquinolines through the post-GBB transformation strategy

• Taofeng Shao,
• Zhiming Gong,
• Tianyi Su,
• Wei Hao and
• Chao Che

Beilstein J. Org. Chem. 2017, 13, 817–824, doi:10.3762/bjoc.13.82

• to structurally complex polycyclic ring systems [33]; an Ugi/aza-Wittig process allowed for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles [34]; the Ugi/Pictet–Spengler sequence provided a rapid and efficient approach to polycyclic natural product-like alkaloids [35]. Accordingly, the

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

• chain elongations of aldoses employing the Henry reaction, the aldol reaction, and the Wittig reaction for the preparation of ketoheptoses [20][21][22], sugar lactones were also often utilized for the synthesis of D-manno-heptulose via reactions with C-nucleophiles or conversion into exocyclic glycals