Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• synthesis of a novel library of 9-alkyl-2-amino-6-triazolylpurine derivatives. Thus, copper-catalyzed azide–alkyne 1,3-dipolar cycloaddition reaction of compounds 6a–c with different para-substituted phenylacetylenes produced the expected compounds 7a–f, 8a–f and 9 (Scheme 1). The yields of 1,3-dipolar

• derivative 4 was synthesized using previously reported procedure of Cu(I)-catalyzed azide–alkyne cycloaddition reaction on 2,6-diazidopurine derivatives [25]. Synthesis of 7-deazapurine derivatives 3, 10a, 11a and their characterization are described in our preliminary communication [39]. Synthesis of 9

• -alkyl-2-pyrrolidino-6-(1,2,3-triazol-1-yl)purine derivatives 7a–f and 9-alkyl-2-piperidino-6-(1,2,3-triazol-1-yl)purine derivatives 8a–f (typical procedure): Alkyne (1.2 equiv) and 10% AcOH water solution (1 mL) were added to a solution of compound 6a (200 mg, 0.61 mmol, 1.0 equiv) in THF (7 mL). The

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• formation of alkylidenecyclopropanes 58a (86%), 58b (60%) and 58c (84%). It is worth mentioning that despite the use of a strong base (KHMDS) and the acidity of the “vinylic” protons of cyclopropenes which is comparable to that of a terminal alkyne [62], cyclopropenylcarbinyl glycolates devoid of

Copper(I)-catalyzed tandem reaction: synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and alkynes

• Muhammad Israr,
• Changqing Ye,
• Munira Taj Muhammad,
• Yajun Li and
• Hongli Bao

Beilstein J. Org. Chem. 2018, 14, 2916–2922, doi:10.3762/bjoc.14.270

• Academy of Sciences, 155 Yangqiao Road West, Fuzhou, Fujian 350002, P. R. China University of Chinese academy of Science (UCAS), Beijing 100190, P. R. China 10.3762/bjoc.14.270 Abstract A copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction for the synthesis of 1,4-disubstituted 1,2,3-triazoles

• research and synthesis of functionalized compounds that have applications in medicinal chemistry, drug discovery, materials chemistry, and as well as in bioconjugates [2][3][4][5][6][7][8][9][10][11][12]. The copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction [13][14][15][16][17][18][19][20][21

• , terminal alkyne 1 (0.5 mmol), diacyl peroxide 2 (0.75 mmol), TMSN3 (90.4 mg, 0.75 mmol), CuCl (4.9 mg, 0.05 mmol) and CH2Cl2 (2 mL) were added, respectively. The reaction mixture was stirred vigorously for 10 h at 50 °C. Then, the reaction mixture was cooled to room temperature, poured into saturated

Dispersion-mediated steering of organic adsorbates on a precovered silicon surface

• Lisa Pecher,
• Sebastian Schmidt and
• Ralf Tonner

Beilstein J. Org. Chem. 2018, 14, 2715–2721, doi:10.3762/bjoc.14.249

• -defined surface chemistry without side reactions and lead to densely packed and well-ordered structures. Cyclooctyne (1), the smallest stable cyclic alkyne, on Si(001) is a system where this is the case and it has previously been thoroughly studied by experiment and theory [6][7][8]. Even though 1 is

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

• system. Domino metathesis of oxa- and aza-norbornenes with alkyne side chains [38][39][40] as well as norbornene derivatives having ether linked alkynes [41][42] in combination with Diels–Alder reaction of the resulting 1,3-dienes have been investigated to construct polycycles with heteroatoms. In spite

• ether 7a in 92% yield. Two different paths can be invoked for metathesis of compound 7a. Metathesis initiation may occur by attack of the ruthenium alkylidene at the alkyne unit to produce the more substituted vinyl alkylidine intermediate 8a which may undergo concomitant ROM–RCM with the norbornene

• acetate 17 also remained inert when subjected to metathesis conditions with G-I as well as with G-II. Neither ring opening of the norbornene nucleus nor cross metathesis of the alkyne with ethylene did occur. To have an understanding about the inertness of 17 towards metathesis we decided to prepare the

Synthesis and biological evaluation of 1,2-disubstituted 4-quinolone analogues of Pseudonocardia sp. natural products

• Stephen M. Geddis,
• Teodora Coroama,
• Suzanne Forrest,
• James T. Hodgkinson,
• Martin Welch and
• David R. Spring

Beilstein J. Org. Chem. 2018, 14, 2680–2688, doi:10.3762/bjoc.14.245

• coupling with commercially available acid chloride 9 according to the previously reported conditions (Scheme 2) [12]. These alkynes were chosen so as to allow access to valuable SAR data regarding the side chain of the natural products 1–8. Commercially available alkyne 10a would ultimately lead to a

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• , a novel competition assay employing ‘clickable’ active-site-labelling probes was developed. These compounds contain terminal alkyne moieties, which can be exploited for straightforward decoration via copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC), the prototypic click reaction. This

Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

• Xiaochen Du,
• Jianjun Huang,
• Anton A. Nechaev,
• Ruwei Yao,
• Jing Gong,
• Erik V. Van der Eycken,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

• . Subjecting these adducts to a gold-catalyzed intramolecular alkyne hydroarylation process allowed to efficiently construct the 2-quinolone core bearing a branched substituent on the nitrogen atom. Keywords: gold catalysis; hydroarylation; 2-quinolones; Ugi reaction; Introduction Quinoline and its oxidized

• nitrogen atom through an intramolecular gold-catalyzed alkyne hydroarylation reaction (Scheme 2). It should be noted, that heterocyclic syntheses through post-Ugi transformations have been under extensive exploration for the last two decades [47][48][49], especially in terms of gold-catalyzed Friedel

• obtained as a mixture with isomer 8r’. As noted above, the intramolecular alkyne hydroarylations with certain Ugi adducts required further adjustment of the reaction conditions. For example, the reaction of substrate 7p being conducted in TFE at room temperature delivered a complex mixture of regioisomeric

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• have also been obtained (TiCl4/Zn [12][13][14][15][16][17] or TiCl3/Zn-Cu [18][19][20]), often as mixture of diastereomers. The use of samarium diiodide to achieve the pinacol coupling was not advised, since we had observed that intially formed ketyl radicals would add to the alkyne moiety [11], even

• motif were prone to aromatization and had to be protected from contact with air and higher temperatures. Removal of solvents was performed below 21 °C and all compounds were stored under argon at −18 °C. Sonogashira coupling (PdCl2(PPh3)2) of dienol triflate 11 with alkyne 12 [11] provided C20 ester 13

• the relative configuration shown in Scheme 4. From cyanohydrin 22 HCN was eliminated by treatment with diluted NaOH (100%, Scheme 3). The resulting ketone 23 reacted with lithiated alkyne 12 affording diastereomerically pure tertiary alcohol 24 (63%) that showed a broad hydroxy signal in the 1H NMR

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• reductant, carboxyzincation and the four-component coupling reaction between alkyne, acrylates, CO2, and zinc occur efficiently. Rh complexes also catalyze the carboxylation of arylboronic esters, C(sp2)–H carboxylation of aromatic compounds, and hydrocarboxylation of styrene derivatives. The Rh-catalyzed

• carboxylation of allylarenes when a suitable ligand is used. In the presence of zinc powder, the Co-catalyzed carboxyzincation of alkynes and the four-component coupling reaction between alkyne, acrylates, CO2, and zinc proceed in an efficient manner. Visible-light-driven hydrocarboxylation reactions are shown

• reduced to Co(I) (A) in the presence of metallic Zn. The oxidative cyclization of A with alkyne 16 and CO2 affords cobaltacycle B (step a). Next, the transmetalation between B and the Zn(II) species occurs, which affords the alkenylzinc intermediate C (step b) [41], which is then reduced with Zn powder

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• ; W2F3, M = W, R = OC(CF3)Me2) were synthesized as bimetallic congeners of the highly active alkyne metathesis catalysts [MesC≡M{OC(CF3)nMe3−n}] (MoF6, M = Mo, n = 2; WF3, M = W, n = 1; Mes = 2,4,6-trimethylphenyl). The corresponding benzylidyne complex [PhC≡W{OC(CF3)Me2}] (WPhF3) was prepared by

• cleaving the W≡W bond in W2F3 with 1-phenyl-1-propyne. The catalytic alkyne metathesis activity of these metal complexes was determined in the self-metathesis, ring-closing alkyne metathesis and cross-metathesis of internal and terminal alkynes, revealing an almost equally high metathesis activity for the

• bimetallic tungsten complex W2F3 and the alkylidyne complex WPhF3. In contrast, Mo2F6 displayed no significant activity in alkyne metathesis. Keywords: alkylidyne complexes; alkyne metathesis; catalysis; terminal alkynes; tungsten; Introduction While the field of olefin metathesis has seen significant

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• and deprotection steps are necessary to control the cyclization process. Preorganization of the molecules can help to make cyclization more efficient. Azide–alkyne "click" chemistry has been executed to generate cyclic peptides [11][12][13], cyclic oligonucleotides [14][15][16][17] and other

• cyclic molecules when alkynyl side chains are functionalizing nucleobases in 5-position and azido substituents replace sugar 5'-hydroxy groups. Cyclic molecules (Figure 1) should be accessible when a copper(I)-azide–alkyne cycloaddition [29][30][31] is performed. The resulting "nucleoides" represent a

• intramolecular cyclization to a macrocycle was not observed. Next, the 5’-azido compound 2 was employed in the copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) "click" reaction [38][39] to build up macrocycle 3. In this regard, two reaction pathways have to be considered: (i) an intramolecular “click

Catalyst-free synthesis of 4-acyl-NH-1,2,3-triazoles by water-mediated cycloaddition reactions of enaminones and tosyl azide

• Lu Yang,
• Yuwei Wu,
• Yiming Yang,
• Chengping Wen and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2018, 14, 2348–2353, doi:10.3762/bjoc.14.210

• ][30][31][32], for example, has served enormously to the advances in both the preparation and application of 1,2,3-triazoles. In addition, the discovery of other metal-catalyzed alkyne–azide cycloadditions (MAAC) providing 1,2,3-triazoles with diverse substitution patterns triggers the continuous

• cycloaddition of azides with activated dipolarophiles such as strained cyclic alkynes, enamines, enolates, electron-deficient olefins, ylides, iminium cations and alkyne anions, etc., have been identified as reliable approaches to access 1,2,3-triazole scaffolds with multiple substitution patterns [39][40][41

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

• -selective reduction [25] of alkyne 20 was easily achieved with sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al) as a hydride-transfer reagent to furnish the corresponding (E)-allylic alcohol 23. A Swern oxidation of 23 provided the corresponding aldehyde which was subjected to an addition reaction with

• alkyne 19 provided the corresponding diynes 25 and 25a in a 1:1 ratio. Though we had an option to proceed further with the mixture of 25 and 25a affording both enantiomers that could be separated later, we focused our attention towards the synthesis of the required chiral compound. Thus, the mixture of

• alcohol 25. ∆δ = δS − δR for the (R)- and (S)-MTPA ester of alcohol 25. Previously proposed and revised structure of strongylodiol H (9). Retrosynthesis of strongylodiols H and I. Synthesis of alkyne 19 and iodo intermediate 21. Reagents and conditions: (a) n-BuLi, THF, −78 °C to rt, 21, 12 h, 72%; (b

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• found intermolecular kinetic isotope effect (KIE) of kH/kD = 2.1 and H/D crossover studies strongly suggest that the reaction proceeds through an oxidative addition of a C–H bond to low-valent cobalt followed by alkyne insertion and reductive elimination. Furthermore, the new C–C bond formation occurred

• -products. Then, coordination of the alkyne with the cobalt catalyst afforded B1 and the oxidative addition of C–H gave the cobalt complex B2. Intramolecular insertion of the Co–H bond into the alkyne and subsequent reductive elimination of the less-hindered alkenyl carbon with aryl group in B3 provides the

• conditions and inexpensive catalyst. The reaction proceeds through an amide-assisted C–H metalation followed by alkyne insertion and protonation [54]. The reaction also acknowledged that the Co(III) species possess unique nucleophilic reactivity compared with the Rh(III) species for the annulation reaction

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• (6) ring threaded onto a water-soluble axle [80]. The rotaxane was synthesized in 23% yield by a template/capping strategy where one stopper is attached using copper-catalyzed azide–alkyne click chemistry after the formation of the precursor pseudorotaxane. Due to the hydrophobic effect, the neutral

• = 6,300 M−1) which is embedded in an axle molecule with two azide residues. The second station, the dihydroxynaphthalene moiety (green), displays a lower association constant of Ka = 5,800 M−1. The pseudorotaxane precursor was end-capped by a double copper-catalyzed azide–alkyne click reaction in CH2Cl2

• . The authors call the stabilizing environment of a [3]catenane a “molecular flask”. However, whereas catenane 29 is directly oxidized from its radical-cation-dimer state (292(●+)) to the fully oxidized 294+ state, the alkyne-based catenane shows a metastable disproportionation equilibrium between the

Revisiting ring-degenerate rearrangements of 1-substituted-4-imino-1,2,3-triazoles

• James T. Fletcher,
• Matthew D. Hanson,
• Joseph A. Christensen and
• Eric M. Villa

Beilstein J. Org. Chem. 2018, 14, 2098–2105, doi:10.3762/bjoc.14.184

• recent years [1][2][3][4][5][6][7], enabled by efficient preparation from the Sharpless–Meldal copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction [8][9][10][11]. Click chelators with a variety of N-donor units connected at the 4-triazolyl position have been reported, including pyridine [12][13

A switchable [2]rotaxane with two active alkenyl groups

• Xiu-Li Zheng,
• Rong-Rong Tao,
• Rui-Rui Gu,
• Wen-Zhi Wang and
• Da-Hui Qu

Beilstein J. Org. Chem. 2018, 14, 2074–2081, doi:10.3762/bjoc.14.181

• +) containing intermediate compound 5 were assembled in dichloromethane through host–guest interaction and capped with compound 8 under Cu(I)-catalyzed azide–alkyne cycloaddition to get the final [2]rotaxane with two distinguishable recognition sites. The target [2]rotaxane R1 was then characterized by 1H NMR

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• , heteroaromatics and aliphatics all seen. However, the variation in the alkyne partner is limited, with only examples of esters and nitriles shown. The yields are variable (15–98%), with no general explanation being offered to rationalise this by the authors. An example of the reaction of two asymmetric substrates

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• /bjoc.14.173 Abstract The synthesis of new calix[4]arenes adopting a cone stereoisomeric form bearing two or four azide fragments on the upper rim and water-soluble triazolyl amphiphilic receptors with two or four polyammonium headgroups via copper-catalyzed azide–alkyne cycloaddition reaction has been

• solutions. Results and Discussion Synthesis of polyammonium calix[4]arene derivatives The functionalization of calix[4]arenes with azide groups paves the way to introduce a wide variety of functional groups [27] on the upper rim of the macrocycle by, e.g., the copper-catalyzed azide–alkyne cycloaddition

Artificial bioconjugates with naturally occurring linkages: the use of phosphodiester

• Takao Shoji,
• Hiroki Fukutomi,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 1946–1955, doi:10.3762/bjoc.14.169

• , Koganei, Tokyo 184-8588, Japan 10.3762/bjoc.14.169 Abstract Artificial orthogonal bond formations such as the alkyne–azide cycloaddition have enabled selective bioconjugations under mild conditions, yet naturally occurring linkages between native functional groups would be more straightforward to

• synthesis, otherwise subsequent steps are complicated. Synthetic chemists, armed with various elegant artificial orthogonal bond formations, including alkyne–azide cycloaddition [27][28][29][30][31][32][33][34], thiol–ene ligation [35][36][37][38], Staudinger ligation [39][40], inverse-electron-demand Diels

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• -responsive LCST changes are very rare, while there have been some examples of LCST control using ionic chemical stimuli [5][6]. Results and Discussion Supramolecular structure and clouding point of bicyclic compound 3 The bicyclic compound 3 was prepared using a copper(I)-catalyzed alkyne–azide cycloaddition

• % [23]. Pillar[5]arene carrying 2 alkyne groups on the same unit (5). In a similar manner as described in [24], 5 was prepared. Under a nitrogen atmosphere, pillar[5]arene carrying one hydroquinone unit 6 [7] (Scheme 1, 417 mg, 0.230 mmol) was dissolved in acetone (10 mL). K2CO3 (159 mg, 1.15 mmol) was

• ), 2.27 (t, 2H, alkyne) ppm; 13C NMR (125 MHz, CDCl3) δ 150.0, 149.8, 149.3, 129.1, 129.0, 128.6, 128.4, 115.6, 115.4, 115.2, 115.1, 71.9, 70.9, 70.8, 70.6, 70.4, 70.3, 68.3, 68.2, 68.1, 68.0, 59.0, 56.5, 29.7, 29.3 ppm; HRMS–ESI (m/z): [M + Na]+ calcd for C97H146NaO34, 1877.9593; found, 1877.9612

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• positively charged nitrogen atoms and π···π donor–acceptor attractions between the phenyl and pyridinium moieties. In our case, the situation is somehow more complex as the novel compounds bear aromatic substituents (via alkyne spacer) in the benzo[b]quinolizinium 9 position. These aromatic substituents now

• along the a axis. In 2a both interactions are with the same neighbor leading to distinct dimeric associates. In the individual molecules, the C–C bond lengths of the alkyne unit are 1.24 Å (C14–C15) for the triple bond and 1.41 Å (C13–C14 and C15–C16) for the single bonds in compound 2a, while in

Efficient catenane synthesis by cucurbit[6]uril-mediated azide–alkyne cycloaddition

• Antony Wing Hung Ng,
• Chi-Chung Yee,
• Kai Wang and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2018, 14, 1846–1853, doi:10.3762/bjoc.14.158

• other recognition units render them promising building blocks for the construction of other high-order interlocked structures. Keywords: azide–alkyne cycloaddition; catenane; click chemistry; cucurbit[6]uril; mechanical bond; Introduction Catenanes are topologically non-trivial molecules possessing

• a preliminary study of a [6]catenane synthesis featuring the CB[6]-mediated azide–alkyne cycloaddition (CBAAC) using phenanthroline-based building blocks [24]. To further explore the applicability and generality of the CBAAC in the construction of mechanically interlocked molecules, we report here

• the efficient synthesis of a series of [3]catenanes from a combination of different azide and alkyne building blocks. These [3]catenanes were obtained in good yields (>85%) with straightforward purification procedures. The good compatibility of CBAAC with these various building blocks and the good

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• additive. Furthermore, Kita and his research group [71] displayed a method for the cyclization of alkyne derivative 58 to spirolactam 59 by an in situ-generated active hypervalent iodine species. In this method, para-substituted amide 58 was cyclized to the corresponding spirolactam 59 in 92% yield using a

• containing an alkyne moiety and sulfonylhydrazides 73 undergo intermolecular spirocyclization in presence of I2O5/TBHP oxidative system to give the sulfonated spirolactams 75 in high yields (Scheme 25). This oxidative system found to be more efficient and could sustain the presence of diverse functional