Ultrasound-promoted organocatalytic enamine–azide [3 + 2] cycloaddition reactions for the synthesis of ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones

• Gabriel P. Costa,
• Natália Seus,
• Juliano A. Roehrs,
• Raquel G. Jacob,
• Ricardo F. Schumacher,
• Thiago Barcellos,
• Rafael Luque and
• Diego Alves

Beilstein J. Org. Chem. 2017, 13, 694–702, doi:10.3762/bjoc.13.68

• ; organocatalysis; organoselenium compounds; sonochemistry; 1,2,3-triazoles; Introduction Substituted 1,2,3-triazoles are an interesting class of heterocyclic compounds distinguished by their biological activities [1][2][3] as well as in various fields of chemistry [4][5][6][7][8][9][10][11][12][13][14][15]. The

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• ; Introduction Isoxazoles are an interesting class of N-heterocyclic compounds intensely studied mainly due to their wide range of biological activity [1][2]. Isoxazole compounds show antiviral [3][4], antithrombotic [5][6][7][8][9], analgesic [9], COX-2 inhibitory [10][11], anti-inflamatory [9][11

• known as reactive 1,3-dipoles involved in 1,3-dipolar cycloaddition reactions with various dipolarophiles generating five-membered heterocyclic compounds, such as isoxazoles, isoxazolines, oxadiazoles, oxadiazolines, dioxazolidines etc. [23][24][25]. Intermediate nitrile oxides are usually generated in

• procedures towards isoxazole derivatives were developed [36][37]. As part of our continued efforts to develop simple synthetic routes towards bioactive heterocyclic compounds [38][39][40][41][42][43], we report here the synthesis of several 3,5-isoxazole derivatives, bearing benzo[1,3]dioxole and thiophene

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• bonds was estimated to be −16.8 kcal/mol whereas the corresponding binding energy for the H2O/Cl− complex was determined to be −15.4 kcal/mol. Electron-deficient heterocyclic compounds such as 1,2,3-triazoles may also serve as strong C–H hydrogen bond donors. Substituted 1,2,3-triazoles possess a

cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

• Dimpee Gogoi,
• Runjun Devi,
• Pallab Pahari,
• Bipul Sarma and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

• the synthesis of carbo- and heterocyclic compounds [21][22][23][24]. The easy accessibility of racemic and enantiomerically pure epoxy substrates through a number of well-established epoxidation methods coupled with procedural simplicity, high atom economy, regio- and stereoselectivity of IFCEA

Synthesis of spiro[isoindole-1,5’-isoxazolidin]-3(2H)-ones as potential inhibitors of the MDM2-p53 interaction

• Salvatore V. Giofrè,
• Santa Cirmi,
• Raffaella Mancuso,
• Francesco Nicolò,
• Giuseppe Lanza,
• Laura Legnani,
• Agata Campisi,
• Maria A. Chiacchio,
• Michele Navarra,
• Bartolo Gabriele and
• Roberto Romeo

Beilstein J. Org. Chem. 2016, 12, 2793–2807, doi:10.3762/bjoc.12.278

• -dipolar cycloaddition process have been rationalized through a mechanistic study on the basis of our expertise in the study of cycloaddition reactions and heterocyclic compounds [37][38][39][40][41][42]. Calculations were performed using the Gaussian09 program package, [43] through optimizations with the

Catalytic Wittig and aza-Wittig reactions

• Zhiqi Lao and
• Patrick H. Toy

Beilstein J. Org. Chem. 2016, 12, 2577–2587, doi:10.3762/bjoc.12.253

• by Marsden (Scheme 14). In their report they also described the synthesis of various other classes of heterocyclic compounds such as 3H-1,4-benzodiazepin-2(1H)-ones 65, 3H-1,4-benzodiazepin-5(4H)-ones 66, and pyrrole 67 from the corresponding starting materials using similar reaction conditions. In

• reduced using diphenylsilane. It is readily evident from the above examples that regardless of whether phosphine or phosphine oxides were used as the catalyst, catalytic aza-Wittig reactions have emerged to become powerful tools in the synthesis of collections of various heterocyclic compounds since it

Sydnone C-4 heteroarylation with an indolizine ring via Chichibabin indolizine synthesis

• Florin Albota,
• Mino R. Caira,
• Constantin Draghici,
• Florea Dumitrascu and
• Denisa E. Dumitrescu

Beilstein J. Org. Chem. 2016, 12, 2503–2510, doi:10.3762/bjoc.12.245

• have been the subject of various reviews [6][7][8][9][10][11][12][13][14][15]. Sydnones 3 are mesoionic heterocyclic compounds with a 1,2,3-oxadiazole skeleton and their chemistry and biological properties are well represented and documented in the literature [20][21][22][23][24][25][26]. The most

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia

• Artem N. Semakin,
• Aleksandr O. Kokuev,
• Yulia V. Nelyubina,
• Alexey Yu. Sukhorukov,
• Petr A. Zhmurov,
• Sema L. Ioffe and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2016, 12, 2471–2477, doi:10.3762/bjoc.12.241

• this case, the primary alkylation adducts might be unstable and undergo heterocyclization reactions (on the synthesis of heterocyclic compounds from azoalkenes and diamines see [54][55][56]). Bishydrazones containing clickable groups (like 3) can be introduced into functional molecules or immobilized

Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)₃ catalyst in the reaction selectivity

• Natividad Herrera Cano,
• Jorge G. Uranga,
• Mónica Nardi,
• Antonio Procopio,
• Daniel A. Wunderlin and
• Ana N. Santiago

Beilstein J. Org. Chem. 2016, 12, 2410–2419, doi:10.3762/bjoc.12.235

• ) trifluoromethanesulfonate; green procedure; heterocycle; Introduction The formation of heterocyclic compounds is a very important task in organic synthesis, mainly because they are present in numerous biologically active compounds and in several natural products [1]. Among them the presence of benzimidazole [2][3][4][5][6

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• further used as synthetic intermediates in numerous synthetic routes to heterocyclic compounds and molecules of biological interest [41][42]. Results and Discussion We first investigated the allylation of diethyl malonate (2a) with the allylic alcohol 1a in DMF in the presence of Pd(OAc)2 (10 mol %), PPh3

Stereoselective synthesis of fused tetrahydroquinazolines through one-pot double [3 + 2] dipolar cycloadditions followed by [5 + 1] annulation

• Xiaofeng Zhang,
• Kenny Pham,
• Shuai Liu,
• Marc Legris,
• Alex Muthengi,
• Jerry P. Jasinski and
• Wei Zhang

Beilstein J. Org. Chem. 2016, 12, 2204–2210, doi:10.3762/bjoc.12.211

• [12][13][14][15][16][17], our lab has introduced a series of synthetic methods for heterocyclic compounds I–VI bearing heterocyclic rings such as hydantoin, pyrrolidine, pyrrolidinedione, piperazinedione, and dihydrobenzodiazepinedione (Scheme 1) [4][18][19][20][21]. All these scaffolds were prepared

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

• suggests that they could be considered as promising candidates for future developments. Keywords: antimicrobial; heterocyclic compounds; natural products; pyrrolidinedione; total synthesis; Introduction Great concern has recently been expressed about the diminishing efficacy of current antibiotic

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

• heterocyclic compounds are produced by a range of actinomycetes and a deeper understanding of their biosynthesis was for a long time hampered by the inability to identify their biosynthetic genes. Those were finally discovered by a comparative genomics approach in which the clusters of thiolactomycin (165

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• [CuCl (0.015 mmol), TEA (0.3 mmol), MeCN, rt, 20 h]. 5 Isocyanide-based multicomponent reactions Although isocyanide-based multicomponent reactions (IMCRs) are one of the most important routes into heterocyclic compounds, there are only a few publications related to the isocyanide-based multicomponent

• . As shown in this review, they play an important role in organophosphorus chemistry where phosphorus reagents are used as substrates for the synthesis of a wide range of phosphorylated heterocycles. In this article, an overview about multicomponent reactions used for the synthesis of heterocyclic

• compounds bearing a phosphonate group on the ring is given. Keywords: multicomponent reactions; organophosphorus chemistry; phosphorus reagents; phosphorylated heterocycles; Introduction Heterocyclic rings are found in many naturally occurring compounds and they compose the core structures of many

Synthesis of highly functionalized 2,2'-bipyridines by cyclocondensation of β-ketoenamides – scope and limitations

• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1170–1177, doi:10.3762/bjoc.12.112

• pyrimidine N-oxide derivatives 7 and 8. Altogether, we could confirm that our approach to functionalized pyridine derivatives by cyclocondensation of β-ketoenamides is also a very versatile and flexible method for the synthesis of unsymmetrically substituted bipyridine derivatives or related heterocyclic

• compounds that are not accessible by alternative methods. Synthesis of highly functionalized 2,2'-bipyridines 4a and 5b from symmetrical 1,3-diketones 1a and 1b; TMSOTf = trimethylsilyl trifluoromethanesulfonate; DIPEA = N,N-diisopropylethylamine; NfF = nonafluorobutanesulfonyl fluoride. Synthesis of β

Iodine-mediated synthesis of 3-acylbenzothiadiazine 1,1-dioxides

• Long-Yi Xi,
• Ruo-Yi Zhang,
• Lei Shi,
• Shan-Yong Chen and
• Xiao-Qi Yu

Beilstein J. Org. Chem. 2016, 12, 1072–1078, doi:10.3762/bjoc.12.101

• 1,1-dioxides were ignored, because of the lack of efficient methods to prepare them. Readily available acetophenones have been shown to be good starting materials for the synthesis of various heterocyclic compounds [20][21][22][23][24]. The Wu group has reported an efficient protocol for the synthesis

A robust synthesis of 7,8-didemethyl-8-hydroxy-5-deazariboflavin

• Matthias Bender,
• Henrik Mouritsen and
• Jens Christoffers

Beilstein J. Org. Chem. 2016, 12, 912–917, doi:10.3762/bjoc.12.89

• compound with high purity. Keywords: carbohydrates; heterocyclic compounds; protective groups; riboflavin derivatives; ribose derivatives; Introduction The deazariboflavin cofactor F420 plays an important role in bacterial methanogenesis [1][2] and was – in contrast to other, ubiquitous biological redox

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• pericyclic mechanism for the formation of heterocyclic compounds in the pyrolysis of aryl azides with unsaturated ortho-substituents. A possible reaction mechanism for the photochemical formation of 2 (Scheme 1, path: 1 → A → 2) based on the report by Platz et al. [54] includes the benzofuroxan formation by

Opportunities and challenges for direct C–H functionalization of piperazines

• Zhishi Ye,
• Kristen E. Gettys and
• Mingji Dai

Beilstein J. Org. Chem. 2016, 12, 702–715, doi:10.3762/bjoc.12.70

• functionalizations, and photoredox catalysis are discussed. We also highlight the difficulties experienced when successful methods for α-C–H functionalization of acyclic amines and saturated mono-nitrogen heterocyclic compounds (such as piperidines and pyrrolidines) were applied to piperazine substrates. Keywords

A practical way to synthesize chiral fluoro-containing polyhydro-2H-chromenes from monoterpenoids

• Oksana S. Mikhalchenko,
• Dina V. Korchagina,
• Konstantin P. Volcho and
• Nariman F. Salakhutdinov

Beilstein J. Org. Chem. 2016, 12, 648–653, doi:10.3762/bjoc.12.64

• the presence of K10 montmorillonite clay forms chiral heterocyclic compounds with the hexahydro-2H-chromene scaffold 2 (Scheme 1) [1][2][3][4]. Products of these reactions are of interest as many of them exhibit a significant analgesic activity in vivo [2][3][4]. In terms of structure–activity

• was 7% (Table 2). Thus, we found for the first time the conditions enabling production of chiral fluoro-containing heterocyclic compounds from a monoterpenoid using the halo-Prins cyclisation. It should also be noted that preparative isolation of compounds of type 7a is complicated by the presence of

Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

• Madhuri Vangala and
• Ganesh P. Shinde

Beilstein J. Org. Chem. 2015, 11, 2289–2296, doi:10.3762/bjoc.11.249

• spirooxazolines are stable and were obtained in good yield with high stereoselectivity due to the conformational rigidity imparted by the 3,4-isopropylidene group. Keywords: fructose; oxazoline; riboside; Ritter reaction; spiro; Introduction 2-Oxazolines represent a unique class of 5-membered heterocyclic

• compounds with a wide range of applications spanning different chemistry disciplines. 2-Oxazoline derivatives are extensively studied due to their presence in numerous bioactive natural products [1][2][3] and synthetic drugs with anticancer, antibiotic, antidiabetic, and antifungal properties (Figure 1, 1–4

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

• 3,4,5,6-tetrachloro-1,2-benzoquinone with methylene-active five-membered heterocyclic compounds: 2-methylbenzoxazoles, 2-methylbenzothiazoles and 2,3,3-trimethylindoline. We have previously reported the synthesis of 2-(benzoxazolyl)-1,3-tropolones, 2-(benzothiazolyl)-1,3-tropolone, 2-(benzoxazolyl)-5,6,7

• solution (method B) is similar to that considered previously for the reaction of o-chloranil with 2-methylquinolines [19] which has been studied by means of DFT PBE0/6-311+G** modelling (Scheme 3, Table 1). At the initial stage, the aldol condensation of the methylene-active heterocyclic compounds with o

• activation energy barrier of the limiting step of the formation of 1,3-tropolone derivatives in the reaction of methylene-active five-membered heterocycles with o-chloranil in acetic acid solution strongly depends on the properties of the fragment X in the heterocyclic compounds. The larger the

Investigation on the reactivity of α-azidochalcones with carboxylic acids: Formation of α-amido-1,3-diketones and highly substituted 2-(trifluoromethyl)oxazoles

• Kandasamy Rajaguru,
• Arumugam Mariappan,
• Rajendran Suresh,
• Periasamy Manivannan and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2015, 11, 2021–2028, doi:10.3762/bjoc.11.219

• . The N-(2-keto)amide skeleton is of particular interest, as it serves as a synthetic precursor for various small heterocyclic compounds such as imidazoles, oxazoles and thiazoles [7][8][9]. Azirine, the smallest nitrogen-containing unsaturated three-membered heterocyclic system, is well known as a

• -azirines are impressive intermediates for the synthesis of various substituted heterocyclic compounds [23][24][25]. Nucleophiles can interact with the electrophilic carbon of the strained 2H-azirine rings and due to the ring strain in the three-membered 2H-azirine ring system A1, the electrophilic

Mechanism, kinetics and selectivity of selenocyclization of 5-alkenylhydantoins: an experimental and computational study

• Biljana M. Šmit,
• Radoslav Z. Pavlović,
• Dejan A. Milenković and
• Zoran S. Marković

Beilstein J. Org. Chem. 2015, 11, 1865–1875, doi:10.3762/bjoc.11.200

• heterocyclic compounds with cyclic urea core, are widely used as intermediates in industrial production of α-amino acids [1]. They exhibit various biological activities making them attractive candidates for drug discovery [2][3][4][5][6][7][8][9][10][11]. In the most cases, the observed biological activities

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

• 24% yield (Scheme 46). Azanorbornene systems 7-Azanorbornene derivatives have been used to generate a wide variety of heterocyclic compounds via the RRM approach [50]. To this end, the azanorbornene derivative 231 was treated with catalyst 2 in the presence of ethylene (24) to produce the heterospiro

• compounds. RRM approach to spiro heterocyclic compounds. RRM approach to regioselective pyrrolizidine system 240. RRM approach to functionalized bicyclic derivatives. RRM approach to tricyclic derivatives 249 and 250. RRM approach to perhydroindoline derivative and spiro system. RRM approach to bicyclic

• approach toward C3-symmetric chiral trimethylsumanene 209. Triquinane synthesis via IMDA reaction and RRM protocol. RRM approach to polycyclic compounds. RRM strategy toward cis-fused bicyclo[3.3.0]carbocycles. RRM protocol towards the synthesis of bicyclic lactone 230. RRM approach to spiro heterocyclic