Diastereoselective synthesis of 3,4-dihydro-2H-pyran-4-carboxamides through an unusual regiospecific quasi-hydrolysis of a cyano group

• Mikhail Yu. Ievlev,
• Oleg V. Ershov,
• Mikhail Yu. Belikov,
• Angelina G. Milovidova,
• Viktor A. Tafeenko and
• Oleg E. Nasakin

Beilstein J. Org. Chem. 2016, 12, 2093–2098, doi:10.3762/bjoc.12.198

• (B) is probably accompanied with decyclization (C) and dehydratation processes forming compound 2 (Scheme 3, path I). However, according to the literature, in most cases, the addition of water to the similar cyclic iminoethers leads to hydrolysis and formation of lactones [26][27]. Another probable

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• acetone are mainly produced by the Hock process, which is based on the rearrangement of cumene hydroperoxide. In 2003, phenol was produced to more than 95% by this oxidation process [52][53][54]. Another important application of organic peroxides is the synthesis of lactones from cyclic ketones via the

• oxidation is widely used in organic synthesis for the preparation of esters and lactones and the Criegee reaction is applied to transform tertiary alcohols into ketones and aldehydes. The Hock rearrangement is a key step in the cumene (cumene–phenol) process and the Kornblum–DeLaMare is an important tool in

• Smith rearrangements are of interest in allyl hydroperoxide transformations. 1.1 Baeyer–Villiger oxidation The BV reaction is the oxidation of ketones or aldehydes A under the action of hydrogen peroxide, hydroperoxides, Caro’s acid (H2SO5), or organic peracids to yield esters, lactones, or carboxylic

Rh-Catalyzed reductive Mannich-type reaction and its application towards the synthesis of (±)-ezetimibe

• Motoyuki Isoda,
• Kazuyuki Sato,
• Yurika Kunugi,
• Satsuki Tokonishi,
• Atsushi Tarui,
• Masaaki Omote,
• Hideki Minami and
• Akira Ando

Beilstein J. Org. Chem. 2016, 12, 1608–1615, doi:10.3762/bjoc.12.157

• α,β-unsaturated lactones, similar β-lactams with anti-selectivities were obtained. Furthermore the yield and anti selectivity could be increased by adding Lewis acid, and we succeeded in achieving the effective synthesis of (±)-ezetimibe by using this reaction. Experimental General information 1H

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• their standard catalytic repertoire (Scheme 1). They transacylate the thioester of a PKS-bound polyketide onto a nucleophile. If the nucleophile is water, this leads to carboxylic acids. The reactions of backbone hydroxy groups or amines consequently give lactones and lactams. TE domains mostly form

• the respective heterocycles. We will not cover medium-sized and macrocyclic lactones and lactams, but concentrate on small heterocycles with ring sizes between 3 and 6 atoms (for a review about macrolactones see reference [12]). Review 1 Oxygen-containing heterocycles Oxygen-containing heterocycles

• are biosynthesised in seven principal ways (Scheme 2). Those comprise nucleophilic addition of a hydroxy group to electrophiles like epoxides 4, carbonyl groups 6 or Michael acceptors 9, potentially followed by further processing (a–c in Scheme 2). Lactones 12 are formed by transacylation of a

Discovery of an inhibitor of the production of the Pseudomonas aeruginosa virulence factor pyocyanin in wild-type cells

• Bernardas Morkunas,
• Balint Gal,
• Warren R. J. D. Galloway,
• James T. Hodgkinson,
• Brett M. Ibbeson,
• Yaw Sing Tan,
• Martin Welch and
• David R. Spring

Beilstein J. Org. Chem. 2016, 12, 1428–1433, doi:10.3762/bjoc.12.137

• types of quorum sensing systems. Two of the QS signaling systems in P. aeruginosa utilise N-acylated-L-homoserine lactones (AHLs) as signalling molecules [20][21][22]. The rhl system utilises N-butanoyl-L-homoserine lactone (BHL) and it’s cognate receptor RhlR [20][21][22]. The las system utilises N-(3

The EIMS fragmentation mechanisms of the sesquiterpenes corvol ethers A and B, epi-cubebol and isodauc-8-en-11-ol

• Patrick Rabe and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1380–1394, doi:10.3762/bjoc.12.132

• the actinobacterium Micromonospora aurantiaca [9] and more than 30 blastmycinones, a class of γ-lactones that depend on the antimycin biosynthetic gene cluster in several streptomycetes [10]. We have also recently developed structural proposals for a series of methylated monoterpenes from the 2

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• reaction. The catalyst 17c showed opposite enantioselectivity when compared to the catalysts 17a and 17b, with the S-enantiomer formed as the major product. In 1991, Doyle and coworkers published asymmetric synthesis of lactones from alkyl diazoacetates in high enantioselectivity by intramolecular rhodium

• carbenoid insertion into C(sp3)–H [40]. In this work, the authors introduced the enantiomeric rhodium(II) carboxamides complexes (R)-18 and (S)-18 (Figure 4). The authors could observe the enantioselective formation of the lactones 20 with high enantiomeric excess (Table 2). The carbenoid formed by (S)-18

• favored the S configuration at the generated stereogenic center for most of the prepared lactones. The opposite preference, R configuration at the new stereogenic center of 20, was reported to the use of the enantiomeric rhodium complex (R)-18. When substrate 19f reacts under catalysis of rhodium(II

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

• halogenated lactones having the 4a,9a-fused skeleton and an ester group at position 1. The cycloaddition reaction proceeded with moderate regio- and stereoselectivity. As reported in the literature, the inverse-electron demand Diels–Alder cycloaddition of unsymmetrical olefins and oxadiazinones [33][34][35

• obtain photoluminescent compounds with higher performance, the dehydrogenation reaction of enol-lactones 2 and 3 was performed. Adapted from a procedure previously described [38], the oxidation of the isomeric mixture 2'a/3''a and 2'c/3'c, respectively, in the presence of 2,3-dichloro-5,6-dicyano-1,4

Three new trixane glycosides obtained from the leaves of Jungia sellowii Less. using centrifugal partition chromatography

• Luíse Azevedo,
• Larissa Faqueti,
• Marina Kritsanida,
• Antonia Efstathiou,
• Despina Smirlis,
• Gilberto C. Franchi Jr,
• Grégory Genta-Jouve,
• Sylvie Michel,
• Louis P. Sandjo,
• Raphaël Grougnet and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2016, 12, 674–683, doi:10.3762/bjoc.12.68

• ) and the partition coefficient calculated for compounds 1 (16.20), 2 (2.77) and 3 (13.51) (Figure 1). Sesquiterpenes were previously reported from the genus Jungia [6][7][24][25][26]. Nevertheless, no glycosylated sesquiterpenes (and sesquiterpene lactones) were previously found in this genus. CPC has

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• formation yielding in the α-pyrone moiety can be accomplished in different ways. The different biosynthetic routes towards an α-pyrone ring will be presented. The biosynthetic mechanisms to yield saturated lactones, like the statin drug lovastatin, which is in application for lowering cholesterol, will not

• was inhibition of porcine Na+/K+-activated ATPase. Germicidin was the first known autoregulative inhibitor of spore germination in the genus Streptomyces [59]. Influence on plant germination was also shown for further lactones. An inhibiting effect was proven for 3,4-dimethylpentan-4-olid from the

New synthetic strategies for xanthene-dye-appended cyclodextrins

• Milo Malanga,
• Andras Darcsi,
• Mihaly Balint,
• Gabor Benkovics,
• Tamas Sohajda and
• Szabolcs Beni

Beilstein J. Org. Chem. 2016, 12, 537–548, doi:10.3762/bjoc.12.53

• University, Hlavova 8, 12843 Prague 2, Czech Republic 10.3762/bjoc.12.53 Abstract Xanthene dyes can be appended to cyclodextrins via an ester or amide bridge in order to switch the fluorescence on or off. This is made possible through the formation of nonfluorescent lactones or lactams as the fluorophore

Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks

• Meriem K. Abderrezak,
• Kristýna Šichová,
• Nancy Dominguez-Boblett,
• Antoine Dupé,
• Zahia Kabouche,
• Christian Bruneau and
• Cédric Fischmeister

Beilstein J. Org. Chem. 2015, 11, 1876–1880, doi:10.3762/bjoc.11.201

• that was further efficiently transformed into a 1,2-diol, a 1,2-alkoxy alcohol and a 1,2-amino alcohol. This strategy opens the way for numerous potential transformations involving the epoxide but also the functional group of the electron-deficient olefin. In particular, lactones should be accessible

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

• 28a,b) in excellent yields (82–92%). Involvement of acrylates 29a,b delivered lactones 30a,b in moderate yields (30a 41%, 30b 50%) upon treatment with catalyst 2 in dichloromethane at reflux conditions. However, 29a generated lactone 30a in 65% yield when the metathesis was performed using Grela’s

• it was monoallylated to deliver an inseparable mixture of products 156 and 157 in 85% combined yield. Later, the mixture (156 and 157) was subjected to a RRM protocol under the influence of the catalyst 1 in the presence of ethylene (24) to yield a mixture (4:1) of tricyclic lactones 158 and 159 (70

Nitro-Grela-type complexes containing iodides – robust and selective catalysts for olefin metathesis under challenging conditions

• Andrzej Tracz,
• Mateusz Matczak,
• Katarzyna Urbaniak and
• Krzysztof Skowerski

Beilstein J. Org. Chem. 2015, 11, 1823–1832, doi:10.3762/bjoc.11.198

• small molecule of ethylene is coordinated to the ruthenium generating highly active methylidene species. Macrocyclization reactions As model substrates for macrocyclization we choose esters 17 and 18 which are metathesized to the 16- and 14- membered lactones. The RCM was run in toluene, at 70 °C and at

Surprisingly facile CO₂ insertion into cobalt alkoxide bonds: A theoretical investigation

• Willem K. Offermans,
• Claudia Bizzarri,
• Walter Leitner and
• Thomas E. Müller

Beilstein J. Org. Chem. 2015, 11, 1340–1351, doi:10.3762/bjoc.11.144

• such as ammonia, hydrogen, epoxides or lactones [8]. Nevertheless, the reactions frequently involve a substantial kinetic barrier or are accompanied by side reactions that, so far, have resulted in insufficient yields and/or selectivities. Even though there are numerous compounds that might react with

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

Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

• Sultan Taskaya,
• Nurettin Menges and
• Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

• acids has been reported in the literature to give the corresponding lactones [33][34][35][36][37][38][39][40]. For example, gold(I)-catalyzed reaction of 2-(phenylethynyl)benzoic acid (8) yielded the exo- and endo-dig cyclization products, lactones 9 and 10 in 62% yield in a ratio of 6:1 (Scheme 1) [41

• internal alkynes, two isomeric E- and Z-oxazinones during the cyclization reaction can be formed. However, we observed exclusive formation of a single isomer. Recently, Michelet et al. [70] and others [41][71][72] demonstrated selectively the formation of Z-lactones. The anti intramolecular addition of the

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• expanded to include α,β-unsaturated ketones, aldehydes, lactones, esters, nitroolefins, and to a lesser extent α,β-unsaturated amides and lactams. Review The lack of development in the CA of α,β-unsaturated amides and lactams is not surprising because these substrates are significantly less reactive than

• (78) ligand for the 1,4-addition of α,β-unsaturated lactones and lactams [148]. With these ligands the desired products were obtained in moderate to excellent yields and good to excellent enantioselectivities. This section illustrates that much work has been done in the development of asymmetric 1,4

Copper-catalyzed cascade reactions of α,β-unsaturated esters with keto esters

• Zhengning Li,
• Chongnian Wang and
• Zengchang Li

Beilstein J. Org. Chem. 2015, 11, 213–218, doi:10.3762/bjoc.11.23

• aldolization followed by a lactonization. This method provides a facile approach to prepare γ-carboxymethyl-γ-lactones and δ-carboxymethyl-δ-lactones under mild reaction conditions. Keywords: aldol addition; cascade reaction; catalysis; conjugate reduction; copper; lactonization; Introduction Paraconic acid

• –lactonization cascade reaction using diethylzinc as a reductant [9]. Floch et al. have reported a catalytic synthesis of the γ-lactones from aryl bromides, zinc, dimethyl itaconate and aldehydes/ketones [10][11], which is characteristic in its simplicity, conciseness and high yielding, however with low

• diastereoselectivity. As expected, a cyclic β-halo-α,β unsaturated aldehyde substrate led to the respective tricyclic lactone, the core structure of strigolactone [12]. Bertrand synthesized β-carboxylic acid-γ-lactones in high yields but with low diastereoselectivity via a dialkylzinc-mediated radical addition to the

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• formation of a C,O-bond and generation of the five-membered heterocycle. Hydroxy, carboxy and oxime moieties were tested as nucleophiles for this reaction, leading to the corresponding tetrahydrofurans, γ-lactones and isoxazolines, respectively. The chemistry depicted in Scheme 13 was also used for the

Synthesis and biological evaluation of novel N-α-haloacylated homoserine lactones as quorum sensing modulators

• Michail Syrpas,
• Ewout Ruysbergh,
• Christian V. Stevens,
• Norbert De Kimpe and
• Sven Mangelinckx

Beilstein J. Org. Chem. 2014, 10, 2539–2549, doi:10.3762/bjoc.10.265

• Michail Syrpas Ewout Ruysbergh Christian V. Stevens Norbert De Kimpe Sven Mangelinckx Department of Sustainable Organic Chemistry and Technology, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium 10.3762/bjoc.10.265 Abstract Novel N-α-haloacylated homoserine lactones, in which a halogen

• atom was introduced at the α-position of the carbonyl function of the N-acyl chain, have been studied as quorum sensing (QS) modulators and compared with a library of natural N-acylated homoserine lactones (AHLs). The series of novel analogues consists of α-chloro, α-bromo and α-iodo AHL analogues

• . Furthermore, the biological QS activity of the synthetic AHL analogues compared to the natural AHLs was evaluated. Halogenated analogues demonstrated a reduced activity in the Escherichia coli JB523 bioassay, with the α-iodo lactones being the less active ones and the α-chloro AHLs the most potent QS agonists

Total synthesis of the proposed structure of astakolactin

• Takayuki Tonoi,
• Keisuke Mameda,
• Moe Fujishiro,
• Yutaka Yoshinaga and
• Isamu Shiina

Beilstein J. Org. Chem. 2014, 10, 2421–2427, doi:10.3762/bjoc.10.252

• -sized lactones (8–11 membered rings) are significant structural motifs because they are found in many natural products possessing useful biological activities [14][15][16][17][18][19]. Among them, the 8-membered (and 9-membered) lactone framework is rather unusual in nature [20][21][22][23][24]. We have

• already developed the synthetic method of lactones with various ring sizes using 2-methyl-6-nitrobenzoic anhydride (MNBA) under mild reaction conditions in the presence of a nucleophilic catalyst such as 4-(dimethylamino)pyridine (DMAP) [25][26]. By using this method, we have demonstrated that unusual

• saturated medium-sized lactones, which are generally difficult to construct because of the ring strain and transannular interactions [27][28], can be effectively prepared [29][30]. Therefore, in order to determine the chemical structure and the expected biological activity of compound 1, we executed the

De novo macrolide–glycolipid macrolactone hybrids: Synthesis, structure and antibiotic activity of carbohydrate-fused macrocycles

• Richard T. Desmond,
• Anniefer N. Magpusao,
• Chris Lorenc,
• Jeremy B. Alverson,
• Nigel Priestley and
• Mark W. Peczuh

Beilstein J. Org. Chem. 2014, 10, 2215–2221, doi:10.3762/bjoc.10.229

• lactone 2 [5], on the other hand, represents one example of glycolipid macrolactone natural products. These novel compounds have many potential applications (e.g., food, cosmetics) based on their physical properties; some glycolipid lactones have also been shown to be cytotoxins [6] and 2 also has

• ], have investigated compounds that blend features of macrolides and glycolipid lactones. These natural product-like compounds fuse the carbohydrate ring to the macrocycle rather than connecting them through a glycosidic linkage. Compounds 3 and 4 in Figure 1 illustrate one approach that has been reported

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• of ketoketenes Using the chiral catalysts (S,Rp)-Josiphos F5 and F6, the Kerrigan group developed the asymmetric homodimerization of ketenes (Scheme 49) [92]. This self-condensation of ketoketenes proceeded in dichloromethane at –25 °C to give chiral β-lactones in high yields (up to 99%) with good to

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• high level of stereocontrol (Scheme 4) [37][38][39][40]. Thus, vicinal and quartenary carbon centers can be obtained in high diasteromeric purity by conjugate additions of allyl, crotyl, and cinnamyl-derived anions to Michael acceptors such as enones, lactones, lactams, and α,β-unsaturated esters

• used for limited exploratory studies. Cyclopropanation and aziridination The cyclopropanation of α,β-unsaturated esters and lactones using chiral phosphonamide reagents is a special case of the conjugate addition–enolate alkylation sequence. The application of chloroallyl phosphonamides such as (trans

• cyclopropane 50a. Starting with (cis,R,R)-47b, the isomeric exo,endo product 50b is obtained as major isomer. The cyclopropanation reaction tolerates a wide range of Michael acceptor subtrates such as enones, lactones, lactams, and acyclic α,β-unsaturated esters. The obtained products can easily be cleaved to