Creating molecular macrocycles for anion recognition

• Amar H. Flood

Beilstein J. Org. Chem. 2016, 12, 611–627, doi:10.3762/bjoc.12.60

• . Again, having a nitrogen atom in the triazole heterocycle instead of a CH provides less steric interference. Finally, the Eu(III) complex was more hydrolytically stable. With the aid of a crystal structure, we saw the smaller size of the triazoles again circumvented the steric destabilization seen in

Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes

• Vladimir A. D’yakonov,
• Alevtina L. Makhamatkhanova,
• Rina A. Agliullina,
• Leisan K. Dilmukhametova,
• Tat’yana V. Tyumkina and
• Usein M. Dzhemilev

Beilstein J. Org. Chem. 2016, 12, 406–412, doi:10.3762/bjoc.12.43

• magnetically active phosphorus atom in the five-membered heterocycle induces the doublet splitting of the carbon signals in the 13С NMR spectra of 2a–h for both the P-substituent and the ring. The highest heteronuclear constants J(31P13C) for the ring, 1JPC ≈ 10–20 Hz, are found for the α-carbon atoms (С-2 and

• than JPC2 = 3.0 Hz in compound 13b. In view of the fact that the phosphorus–carbon constants obey the Karplus equation [22], this result suggests that the conformation of the five-membered heterocycle changes upon the formation of the complex with molybdenum hexacarbonyl. Similarly, bisphospholanes 10a

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

• Ping Qian,
• Bingnan Du,
• Wei Jiao,
• Haibo Mei,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

• heterocycle formation reaction of N-allylbenzamide with alcohols as radical partners. This provided 4-hydroxyalkyl-substituted 3,4-dihydroisoquinolin-1(2H)-one derivatives (Scheme 1b) [44]. Based on the knowledge gained from previous reports on the cyclization of N-allylbenzamide [44], we envisioned that the

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• (ROESY) analysis. Pesticides bearing a nitrogen heterocycle The association constants of chlorpyrifos (4, Figure 3) with β-CD, HP-β-CD, and 6-O-α-maltosyl-β-CD hydrate (G2-β-CD) in aqueous media were determined by photochemically induced fluorescence (PIF, Table 1) [39][46]. Results are summarized in

Copper catalysis in organic synthesis

• Sherry R. Chemler

Beilstein J. Org. Chem. 2015, 11, 2252–2253, doi:10.3762/bjoc.11.244

• Ullmann and Goldberg couplings, asymmetric acetylide additions to carbonyl groups, radical alkylations and asymmetric conjugate additions as well as original contributions in the area of copper-catalyzed C–C cross-coupling, conjugate additions, allylic alkylations, alkene difunctionalizations, heterocycle

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• heterocycle, the pyrimidine ring was disclosed as useful DG in copper-catalyzed C–H activation. As reported by Shen and co-workers [60], the C–H bond in indoles 47 and benzenes 48 could be effectively activated with copper in the presence of DGs such as pyrimidin-2-yl, pyridine-2-yl or benzoyl to provide

• on the electron deficient reactants such as 2-methylpyridine, 2-methylquinoline, 2-methylquinoxalines, 2-methylthiazole and 2-methylbenzothiazole, other methylated heterocycle such as 3-methylpyridine was not tolerated (Scheme 24) [81]. Similar quinaxolinone products were also successfully

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• -closing step preceded by the formation of the norcaradiene intermediates 8 must include the stage of the proton transfer from the methylene group of the intermediate adduct 7 to the nitrogen atom of the heterocycle. The double proton transfer resulting in the (7A∙AcOH) → (7B∙AcOH) isomerization is the

Photoinduced 1,2,3,4-tetrahydropyridine ring conversions

• Baiba Turovska,
• Henning Lund,
• Viesturs Lūsis,
• Anna Lielpētere,
• Edvards Liepiņš,
• Sergejs Beljakovs,
• Inguna Goba and
• Jānis Stradiņš

Beilstein J. Org. Chem. 2015, 11, 2166–2170, doi:10.3762/bjoc.11.234

• has a large reorganization energy for electron transfer [38][39], the reverse reaction may be retarded, promoting to the subsequent heterocycle conversions. Conclusion Several synthetic routes have been explored towards chiral hydroperoxides as they have been utilized successfully in a variety of

• . Photoinduced reaction of 1 in O2 saturated CHCl3 under irradiation by intensive sunlight. Heterocycle transformations of 1 in air saturated CHCl3 solutions. Proposed mechanism of conversion of oxaziridine 4 to 5. Supporting Information Synthesis and characterization of all products, copies of 1H and 13C NMR

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

• substituted cyclopropene such as 19 (or 20) was treated with catalyst 2 in the presence of ethylene (24) the required heterocycle 22 (or 23) was obtained in moderate to good yield (Scheme 2) [8]. Allyl ethers 25a,b and 26a,b were reacted with catalyst 2 to deliver the corresponding dihydrofurans (27a,b and

• catalyst 7. Pyrrolines were produced in excellent yields by RRM of sulfonamides 31a,b using the catalyst 2 under dichloromethane reflux conditions (32a 99%, 32b 70%) (Scheme 3). Five-membered heterocycles such as 34 and a seven membered heterocycle 35 in 40:60 ratio (97%) were formed by RRM of

• required building block 85 has been prepared from compound 84 by allylation with allyl bromide (37). Later, the pyran derivative 85 was treated with catalyst 2 to generate the bicyclic system 86 (73%) (Scheme 17). They also demonstrated a RCM–ROM–RCM cascade using a strain-free allyl heterocycle as useful

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

• . Thus, RCM with substrate 7 having one double bond terminally substituted with the phenyl ring as well as the formation of the trisubstituted heterocycle 9 proceeded better with chloride-containing catalysts. When proline derivative 10 was used, the diiodo catalysts performed better than nG but slightly

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• ) can be constructed by building up either of its two rings, involving cyclisation of a suitable precursor already containing one existing heterocycle. The construction of the 1,3-dithiole-2-thione unit of 17 can be completed using 3,4-dibromothiophene (18) as a starting material [56], or by oxidation

A new and efficient procedure for the synthesis of hexahydropyrimidine-fused 1,4-naphthoquinones

• Marcelo Isidoro P. Reis,
• Vinícius R. Campos,
• Jackson A. L. C. Resende,
• Fernando C. Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2015, 11, 1235–1240, doi:10.3762/bjoc.11.137

• ]quinazoline; microwave; naphthoquinone; 1,3-quinazoline; 1,3,5-triazinane; Introduction Quinones represent a diverse family of naturally occurring secondary metabolites [1][2][3]. Interest in these substances has intensified in recent years due to their pharmacological importance [4]. Heterocycle-fused

• demonstrated to display various biological activities. There are several specific and general methods reported in the literature that describe the preparation and biological activity of heterocycle-fused naphthoquinone compounds [35]. Recently, Iida et al. described a general method for the construction of

• pyrrole-, furan- and thiophene-fused naphthoquinones [36]. For several years, our group has been interested in developing new synthetic methods for the preparation of heterocycle-fused 1,4-naphthoquinones or heterocycle-tethered 1,4-naphthoquinones. 1,3-Quinazolines are nitrogenated heterocycles that are

Synthesis of icariin from kaempferol through regioselective methylation and para-Claisen–Cope rearrangement

• Qinggang Mei,
• Chun Wang,
• Zhigang Zhao,
• Weicheng Yuan and
• Guolin Zhang

Beilstein J. Org. Chem. 2015, 11, 1220–1225, doi:10.3762/bjoc.11.135

• cyclization in route 1, and therefore enhances the proportion of the para-rearrangement product 8. Obviously, strong alkali could lead to heterocycle cleavage of the flavonoid skeleton. Gratifyingly, when prenyl ether 8 was treated with catalytic amounts of Eu(fod)3 and NaHCO3 in PhCl at 85 °C for 24 h (Table

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• valves so that the second loop transfers the reagent, whilst the first one is being recharged. This concept was successfully applied to the flow synthesis of a 20-member library of casein kinase I inhibitors (38) that also demonstrate the selective mono-bromination, heterocycle formations and high

Donor–acceptor type co-crystals of arylthio-substituted tetrathiafulvalenes and fullerenes

• Xiaofeng Lu,
• Jibin Sun,
• Shangxi Zhang,
• Longfei Ma,
• Lei Liu,
• Hui Qi,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 1043–1051, doi:10.3762/bjoc.11.117

• -crystal; donor–acceptor system; fullerene; Introduction Tetrathiafulvalene (TTF) [1][2][3] and its derivatives have attracted significant interest for decades. This is because this unique heterocycle system has provided most of the organic conductors possessing diverse electronic ground states [4][5][6

Highly selective palladium–benzothiazole carbene-catalyzed allylation of active methylene compounds under neutral conditions

• Antonio Monopoli,
• Pietro Cotugno,
• Carlo G. Zambonin,
• Francesco Ciminale and
• Angelo Nacci

Beilstein J. Org. Chem. 2015, 11, 994–999, doi:10.3762/bjoc.11.111

• their ability of acting as a σ-donor towards the metal. In particular, the higher the aromatic character of the heterocycle the lower is the back-donation by palladium, and this effect would enhance the electron density on the metal rendering it more reactive. On these bases, we can speculate that the

Synthesis of carbohydrate-scaffolded thymine glycoconjugates to organize multivalency

• Anna K. Ciuk and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2015, 11, 668–674, doi:10.3762/bjoc.11.75

• , it is known that the thymine heterocycle can be easily N3-alkylated with, for example, bromoalkyl glycosides. This reaction can be used to install specific sugar moieties for biological recognition [5]. Hence, thymine was employed as the photosensitive control element, a functionalized mannoside was

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• embedded 2,2’-diindolic core, has resulted in rapid access to new examples of the hydroxy-8a,13-dihydroazepino[1,2-a:3,4-b']diindol-14(8H)-one skeleton in up to 51% yield. Additionally a derivative of the novel bridged heterocycle 7,8-dihydro-6H-6,8a-epoxyazepino[1,2-a:3,4-b']diindol-14(13H)-one was

• slightly bent orientation to each other, with the 7-membered ring in the same curved line. The 5-membered tetrahydrofuryl ring is disposed orthogonally to the curved backbone and is in a puckered conformation, typical of 5-membered aliphatic rings. The heterocycle is stable at room temperature and to air

• of the bicyclic heterocycle 22 comes from analysis of computational models of the proposed starting materials to cyclisation (i.e., alcohol 10) and the bridged products, e.g., 22 (Table 1). The ΔHf of the gem-dimethyl substrate 10 (262.7 kJ/mol) is remarkably similar to the product bicycle 22 (263.0

Ruthenium-catalyzed C–H activation of thioxanthones

• Danny Wagner and
• Stefan Bräse

Beilstein J. Org. Chem. 2015, 11, 431–436, doi:10.3762/bjoc.11.49

• (styrene, vinyl/allyl ethers, perfluoroalkylethenes) failed since they polymerize during the reaction. Extension of the unsymmetrical heterocycle system 1b to the unsubstituted thioxanthone (1a) was also successful: Depending on the amount of alkene, mono- (Table 2, entry 3) or 1,8-disubstituted

Bis(vinylenedithio)tetrathiafulvalene analogues of BEDT-TTF

• Erdal Ertas,
• İlknur Demirtas and
• Turan Ozturk

Beilstein J. Org. Chem. 2015, 11, 403–415, doi:10.3762/bjoc.11.46

• at the both ends of the molecule, it has a non-planar structure [42]. π-Extended molecules such as 4 with a vinylene group at the end of the BEDT-TTF unit have more planar structures [41][43]. Further, a tetrathiafulvalene with a fused aromatic heterocycle was synthesized as a π-extended donor

The reactions of 2-ethoxymethylidene-3-oxo esters and their analogues with 5-aminotetrazole as a way to novel azaheterocycles

• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess and
• Viktor I. Saloutin

Beilstein J. Org. Chem. 2015, 11, 385–391, doi:10.3762/bjoc.11.44

• –N8 bond, tetrazolo[1,5-a]pyrimidine D undergoes azide–tetrazole isomerism to form isomeric 2-azidopyrimidines 2a–c. The electron-withdrawing substituents in the heterocycle are known to facilitate the opening of the fused tetrazole ring because of decreased electron density at the bridgehead nitrogen

• . The structure of bis-heterocycle 3 was confirmed by 1H and 13C NMR spectra, including 2D 1H,13C HSQC/HMBC experiments. So, in the 13C NMR spectrum the signal of C-3a carbon of the one heterocyclic fragment was observed at δ 149.71 ppm, which is characteristic of the bridgehead carbon atom in 4,7

• ) in tetrazolopyrimidine fragment, as well as cross-peaks between H-6’ proton (δ 9.02 ppm) and C-5’ (δ 120.17 ppm) and C-2’ (δ 163.41 ppm) carbons in azidopyrimidine system supported structure 3. The formation of bis-heterocycle 3 is due to the unique structure of the starting 2-azidopyrimidine 2c

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

• Natalia A. Danilkina,
• Petr S. Vlasov,
• Semen M. Vodianik,
• Andrey A. Kruchinin,
• Yuri G. Vlasov and
• Irina A. Balova

Beilstein J. Org. Chem. 2015, 11, 373–384, doi:10.3762/bjoc.11.43

• ). These experiments revealed that both bromine atoms at pyridazine and benzene rings are highly reactive in the Sonogashira coupling due to the strong activation of the electron deficient nature of the heterocycle. Having starting compounds 5a,b in hand, we were ready to carry out the polycondensation

Selective methylation of kaempferol via benzylation and deacetylation of kaempferol acetates

• Qinggang Mei,
• Chun Wang,
• Weicheng Yuan and
• Guolin Zhang

Beilstein J. Org. Chem. 2015, 11, 288–293, doi:10.3762/bjoc.11.33

• result in heterocycle cleavage of the flavonoid skeleton. To obtain 3,7-di-O-methylkaempferol (7), we envisioned the possibility of methylation from the 4′-O-acetylkaempferol (6), which can be derived from 2. We were delighted that the combination of reflux with aluminum chloride in polar solvent CH3CN

The unexpected influence of aryl substituents in N-aryl-3-oxobutanamides on the behavior of their multicomponent reactions with 5-amino-3-methylisoxazole and salicylaldehyde

• Volodymyr V. Tkachenko,
• Elena A. Muravyova,
• Sergey M. Desenko,
• Oleg V. Shishkin,
• Svetlana V. Shishkina,
• Dmytro O. Sysoiev,
• Thomas J. J. Müller and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2014, 10, 3019–3030, doi:10.3762/bjoc.10.320

• ; catalysis; chemoselectivity; heterocycle; multicomponent reaction; ultrasonication; salicylaldehyde; Introduction Generally, considerable interest in heterocyclic compounds is due to their key role in biological processes in nature and biological activity. In particular, condensed heterocycles bearing a

• substitution of the salicylic hydroxy group leading to the oxygen-bridged heterocycle 6. Apparently the oxygen-containing ortho-substituent on the benzene ring adopts an important role in the central ion coordination. At first glance, the behavior of N-(2-hydroxyphenyl)-3-oxobutanamide (3h) in the three

• ), salicylaldehyde (2) and N-(2-methoxyphenyl)-3-oxobutanamide (3a). Optimization of the reaction conditions for obtaining compound 5a. Optimization of the reaction conditions for heterocycle 6a synthesis. Three-component heterocyclization of 5-amino-3-methylisoxazole (1), salicylaldehyde (2) and N-aryl-3

A one-pot multistep cyclization yielding thiadiazoloimidazole derivatives

• Debabrata Samanta,
• Anup Rana,
• Jan W. Bats and
• Michael Schmittel

Beilstein J. Org. Chem. 2014, 10, 2989–2996, doi:10.3762/bjoc.10.317

• unit. The structure of the intricate heterocycle 2a was confirmed by single-crystal X-ray analysis and its mechanism of formation supported by DFT computations. Keywords: carbodiimide; cyclization; dithiourea; DFT; 1,2,4-thiadiazoles; Introduction Heterocyclic rings are key components in many