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Difunctionalization of strained cyclic alkynes presents a powerful strategy to build richly functionalized cyclic alkenes in an expedient fashion. Herein we disclose an efficient and flexible approach to achieve carbohalogenation, dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates. We have demonstrated the novel use of zincate base/nucleophile system for effective formation of key cyclohexyne intermediates and selective addition of various carbon and nitrogen nucleophiles. Importantly, leveraging the resulting organozincates enables the incorporation of a broad range of electrophilic partners to deliver structurally diverse cyclohexene motifs. The importance and utility of this method is also exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.

The chemical functionalization of polyolefins to access responsive materials is a long-standing challenge in materials science. Current protocols do not typically tolerate polar functional groups, ...

A convenient metal-free photocatalytic hydrosilylation of a variety of linear and cyclic alkenes has been investigated. It was found that the free radical type photoinitiator Irgacure 2959 had a better effect on the hydrosilylation reaction; using 3 mol% photoinitiator Irgacure 2959, higher conversion rates can be obtained in the hydrosilylation of both some internal and terminal olefins. A new green method for hydrosilylation processes is achieved.

Efficient methods for the dicarbofuntionalization of the cyclic alkenes 2-pyrroline and 2-azetine are limited. Particularly, the dicarbofunctionalization of endocyclic enecarbamates to achieve fluorinated compounds remains an unsolved issue. Reported here is a nickel-catalyzed trans-selective dicarbofunctionalization of N-Boc-2-pyrroline and N-Boc-2-azetine, a class of endocyclic enecarbamates previously unexplored for transition metal catalyzed dicarbofunctionalization. The reaction can be extended to six- and seven-membered endocyclic enamides. A variety of arylzinc reagents and bromodifluoroacetate, and its derivatives, undergo the reaction, providing straightforward and efficient access to an array of pyrrolidine- and azetidine-containing fluorinated amino acids and oligopeptides, which may have applications in the life sciences.

A highly stereo- and regioselective synthesis of the core skeleton of hexahydrobenzo[c]phenanthridine-type alkaloids is reported herein for the first time. A wide range of substrate scope, excellent functional group tolerance, and good to excellent yields were observed. This protocol gives very concise and efficient access to the core skeleton of chelidonine alkaloids as compared to the earlier approaches.

The Pt-catalyzed diboration of cyclic alkenes is extended to unsaturated heterocycles and bicyclic compounds and can be accomplished in a diastereoselective fashion. The optimal procedures, substrate scope, and diastereoselectivity were investigated, and examples employing both homogeneous and heterogeneous catalysis were examined. Lastly, application to the construction of the nucleoside analog (±)-aristeromycin was conducted.

We report on the synthesis of an alkane-soluble Zintl cluster, [η4-Ge9(Hyp)3]Rh(COD), that can catalytically hydrogenate cyclic alkenes such as 1,5-cyclooctadiene and cis-cyclooctene. This is the first example of a well-defined Zintl-cluster-based homogeneous catalyst.

A Cu(I) complex of bisamidine-type sp2N bidentate ligand, Naph-diPIM, catalyzes coupling between 1,3-dicarbonyl compounds and simple cyclic alkenes using (t-BuO)2, providing the corresponding C-all...

An easy approach to N-hydroxy-N-cycloalkenylamides, ene adducts of cyclic alkenes of different sizes, is presented. The products can be obtained both through the thermal generation of the nitrosocarbonyl intermediates and via the photochemical fragmentation of the Wieland heterocycle, this being the mildest way to generate these fleeting species, also affording the best results so far in terms of chemical yields. The use of the ene reaction for the synthesis of biologically active molecules represents an interesting and valuable aspect of modern organic synthesis, and this is the strategy proposed as a remarkable alternative to current methods.

A three-step synthesis of β-alkoxy-substituted alicyclic sulfonyl chlorides from cyclic alkenes and alcohols is reported. The scope of the method was studied for a range of the substrates with various steric and electronic properties. The title compounds were obtained on a hundred-gram scale in up to 52% overall yield scale as single cis-diastereomers.

Equal concentration mixtures of p-chlorophenol and a sulfosuccinic surfactant bis(2-ethylhexyl)sulfosuccinate (AOT) are known to form optically clear gels in cyclic organic solvents like cyclohexane, whereas turbid gels are obtained in acyclic alkanes and aromatic solvents with the same gelators. Clear organogels are necessary when emitting devices are dispersed inside the gel. As such, in this study, we employed 16 cyclic solvents including cyclic alkanes, cyclic alkenes, cycloalkanones, and chlorocyclohexane. Eventually we were to obtain clear gels in 12 cyclic alkane and cyclic alkene solvents at immediately after the gelation, while 2 of those gels turned out to be turbid in a few days. A cyclic solvent geometry was shown to be unnecessary to obtain clear gels. Transmittance spectra, drop-point temperature, and nuclear magnetic resonance were employed to characterize the organogels. The rigid structure in the π-stack caused by p-chlorophenol self-assembly brought about a higher drop point.

The development of a Lewis acid-catalyzed ring-opening cross-metathesis reaction which enables selective access to acyclic, unsaturated ketones as the carbonyl–olefin metathesis products is described. While catalytic amounts of FeCl3 were previously identified as optimal to catalyze ring-closing metathesis reactions, the complementary ring-opening metathesis between cyclic alkenes and carbonyl functionalities relies on GaCl3 as the superior Lewis acid catalyst.

1,2-Bifuctional thiocyanodiphenylphosphinoylation of alkenes is established through the phosphinoyl radical addition followed by Cu-catalyzed thiocyanation. This one-pot reaction is applicable to a range of aromatic, aliphatic, and cyclic alkenes to afford thiocyanodiphenylphosphinoylated compounds in satisfactory yields.

The chemistry of strained unsaturated cyclic compounds has experienced remarkable growth in recent years via the development of metal–free click reactions. Among these reactions, the cycloaddition of cyclopropenes and their analogues to ortho-quinones has been established as a highly promising click reaction. The present work investigates the mechanism involved in the cycloaddition of strained dienes to ortho-quinones and structural factors that would influence this reaction. For this purpose, we use B97D density functional theory calculations throughout, and for relevant cases, we use spin component–scaled MP2 calculations and single–point domain-based local pair natural orbital coupled cluster (DLPNO-CCSD(T)) calculations. The outcomes are analyzed in detail using the distortion/interaction model, and suggestions for future experimental work are made.

The concept of a novel type of homoconjugation, henceforth referred to as columnar homoconjugation, is introduced. A new class of organic molecules which is expected to exhibit such interaction is devised; for this series, the name "columnene" is coined. Molecular Orbital calculations (HQckel, MNDO, and/or ab initio) for a series of columnenes as well as cyclic alienes, cyclicbutatrienes, and trans cyclic alkenes olefins are reported. These calculations lead to the prediction that alkene moieties easily withstand slight twisting and bending destabilization. Synthetic strategies towards columnenes are developed and are categorized by two approaches: butatriene and bisallyl synthetic equivalent approaches. The utility of the butatriene synthetic equivalent approach for the synthesis of benzocyclobutenes is demonstrated. The first synthesis of 1,2,3-cyclononatriene, inspired by the results of MO calculations, is reported; the molecule is further characterized by complexation with Wilkinson's catalyst.

WOS: 000350221600019 A novel protocol for the practical and green synthesis of vicinal cis-diols from 10.0 mmol olefins by using 5.0 mmol KMnO4 as oxidant and 30.0 mmol H2O2 as co-oxidant is reported. The presented procedure is easy to carry out and enables the direct transformation of linear and cyclic alkenes to the corresponding vicinal cis-diols. The synthesis of vicinal cis-diols by dihydroxylation of olefins with a KMnO4/H2O2 system was catalyzed by in situ generatedMnxOy nanoaggregates. The use of H2O2 as a co-oxidant is the key for the protocol to synthesize vicinal cis-diols in high yields, because it assists the oxidation of MnxOy nanoaggregates, which have an active role in the oxidation reaction medium. Ataturk UniversityAtaturk University [2013/82] We thank Assoc. Prof. Dr Onder Metin for his help with the TEM, SEM, XRD, XPS, EDX, BET and BJT studies and proofreading. This work was supported by the Ataturk University under project no. 2013/82.

A novel synthesis of CF3-containing spirooxazolines and spirooxazines has been developed. Regiospecific trifluoromethylative spirocyclization (CF3-spirocyclization) of cyclic alkenes bearing an amide pendant mediated by photoredox catalysis is a useful strategy for construction of a C(sp(3))-CF3 bond and an spirooxazoline or spirooxazine ring onto C═C bonds via a single step. The key intermediate is α-CF3-substituted carbocationic species smoothly generated from single-electron-transfer (SET) photoredox processes, which results in diastereoselective spirocyclization. This is the first example of synthesis of CF3-containing spirooxazolines and spirooxazines in anti-fashion with respect to the CF3 group and the oxygen atom of the spirocycles.

We report a radical-mediated skeletal reorganization for the synthesis of medium-/large-sized cyclic alkenes., Although great success has been achieved in selective C–C bond cleavage via the intramolecular radical remote migration process of several carbon-based groups, the development of the radical-based remote vinyl migration process remains a formidable challenge because of the energetically unfavorable process. To address this problem, we report here, for the first time, a novel C–C bond reorganization strategy via an unprecedented radical 1,3-, 1,4-, or 1,5-vinyl migration triggered by various types of fluoroalkylation of alkenes for the efficient realization of 1,2-fluoroalkylalkenylation reaction. This strategy provides an expedient and broadly applicable platform to access skeletally and functionally diverse fluoroalkyl-containing medium- and large-sized cyclic alkenes with excellent chemo-, regio-, and stereoselectivity. The broad substrate scope, which covers distinctly electron-neutral or electron-deficient alkenyl migrating groups and various fluoroalkyl radical precursors, the excellent functional group tolerance, the remarkable selectivity, and the operational simplicity, as well as versatile transformations of the products, make this approach practical and attractive.

Co-catalyzed epoxidation of cyclic alkenes proceeds in ionic liquid media (1-ethyl-3-methylimidazolium hexafluorophosphate). Epoxidation of the alkenes to respective epoxides was greatly accelerated by the use of a cobalt-based catalyst in the presence of H2O2 as an oxidant. The catalyst in ionic liquid [Emim]PF6 was recycled and reused for about seven times.

A mild and efficient protocol for the preparation of bromoformates as well as bromoacetates from olefins using NH4Br and oxone® in nucleophile sources (DMF or DMA) without employing catalyst at room temperature is described. This method is facile, environmentally friendly and cost effective. A variety of terminal, internal and cyclic alkenes reacted smoothly to give the corresponding bromoformate and acetate products in good to excellent yields. Moreover, 1,2-disubstituted olefins provided moderate to excellent diastereoselectivity.

An effective method for Pd-catalyzed cross-coupling between polyfluoroarenes and cyclic vinyl triflates has been developed. This protocol provides a useful and facile access to polyfluoroarylated cyclic alkenes that are difficult to prepare otherwise. The advantages of this method are its high efficiency and operational simplicity.

A mild and efficient protocol for the preparation of 1,2-dichloroalkane derivatives from olefins using NH4Cl and Oxone® at room temperature is described. A variety of terminal, internal, and cyclic alkenes reacted smoothly to give the corresponding dichlorinated products in good to excellent yields. Moreover, 1,2-disubstituted symmetrical and unsymmetrical olefins dichlorinated with moderate to excellent diastereoselectivity. This method precludes the use of acidic additives and transition metals in the synthesis of vicinal dichlorides.

Radical addition reaction of trifluoromethyl-1,3-dicarbonyl compounds (1a-e) with various alkenes (2a-f) was investigated in the presence of manganese(III) acetate. As a result of these reactions trifluoromethyl ketone substituted dihydrofuran and bicyclic enol ether derivatives were obtained. A formation of dihydrofuran's mechanism was proposed for all compounds. Radical addition reactions with 1,1-disubstituted alkenes were obtained in good yields, however with cyclic alkenes were shown poor yields.

The efficient protocol tolerates various alkenes, such as 1-substituted and 1,1-disubstituted styrene derivatives and cyclic alkenes.

The 2-thienyl-substituted 4,5-dihydrofuran derivatives 3–8 were obtained by the radical cyclization reaction of 1,3-dicarbonyl compounds 1a–1f with 2-thienyl-substituted conjugated alkenes 2a–2e by using [Mn(OAc)3] (Tables 1–5). In this study, reactions of 1,3-dicarbonyl compounds 1a–1e with alkenes 2a–2c gave 4,5-dihydrofuran derivatives 3–5 in high yields (Tables 1–3). Also the cyclic alkenes 2d and 2e gave the dihydrobenzofuran compounds, i.e., 6 and 7 in good yields (Table 4). Interestingly, the reaction of benzoylacetone (=1-phenylbutane-1,3-dione; 1f) with some alkenes gave two products due to generation of two stable carbocation intermediates (Table 5).

A facile access to perhydroindole and related scaffolds via a highly efficient Pd-catalyzed intramolecular cyclization of oxime esters with cyclic alkenes is given.

Starting from cyclic alkenes bearing an amide tether the title reaction provides trifluoromethylated spirooxazolines or spirooxazines in moderate to high yields and with moderate to high anti-diastereoselectivity.

Linear and cyclic alkenes are directly transformed to the corresponding vicinal cis-diols by dihydroxylation with a KMnO4/H2O2 system.

The oxidative C—H cross coupling of arenes or hetarenes with linear or cyclic alkenes proceeds with the use of the in situ generated, highly electrophilic Pd-species, e.g. [Pd(TFA)2].

Cycloadditions of N-methyl-C-(diethoxyphosphoryl)nitrone 1a to cyclic alkenes proceeded regio- and diastereospecifically. Reactions of 1a with 1,1-disubstituted alkenes led to the regiospecific formation of 5,5-disubstituted isoxazolidines 7/8 in nearly equimolar ratios, whereas additions to trans-1,2-disubstituted alkenes gave four isomeric isoxazolidines with up to 80% regioselectivity and moderate (up to 60%) diastereoselectivity. Stereochemistry of the substituted isoxazolidines was established based on the conformational analysis using vicinal H–H, H–P and P–C couplings, and was, in some cases, supported by geminal H–C–P O coupling and deshielding P O and C O effects.

The aza-Diels–Alder reactions of two 2-aminophenols in combination with six substituted benzaldehydes and two electron-rich cyclic alkenes were investigated under controlled microwave heating. The reactions were carried out in the presence of a catalytic amount of CF 3 CO 2 H in MeCN at 60 °C for 15 min, affording highly functionalized 8-hydroxy-1,2,3,4-tetrahydroquinolines in 39–59% isolated yields and in 36:64–16:84 diastereomer ratios in favor of the trans isomers. The microwave-heated three-component aza-Diels–Alder reactions completed in significantly reduced reaction time to give the same level of chemical yield and diastereomer ratio obtained from the room temperature reaction.

A new type of bisoxazoline ligand 4 (abbreviated as SpiroBOX) containing a chiral spirobiindane scaffold were easily prepared in high yields from enantiomerically pure 1,1′-spirobiindane-7,7′-diol (SPINOL) with 1,1′-spirobiindane-7,7′-dicarboxylic acid as the key intermediate. Ligands 4 were applied to the Cu-catalyzed asymmetric cyclopropanation of styrenes with menthyl diazoacetate and allylic oxidation of cyclic alkenes with tert-butyl perbenzoates. The copper complexes of ligands 4 showed high activities and moderate to good enantioselectivities.

Aroyl chlorides react with acyclic and cyclic alkenes in the presence of a rhodium catalyst to give Mizoroki–Heck type and cyclization products, respectively. A rhodium-ethylene complex, [{RhCl(C2H4)2}2], showed excellent performance for these reactions. Notably, the reactions can be conducted effectively under base- and phosphane-free conditions.

Regioselective synthesis of α‐iodoacetates from alkenes, ammonium acetate, and iodine in acetic acid is reported. The reaction is facile, fast, environmentally, friendly, and cost effective. α‐Iodoacetates are obtained from both acyclic and cyclic alkenes in high yields ranging from 80–95% within 10–20 min.

The thermal cycloaddition of beta-disulfonyl iodonium ylides to cyclic alkenes affords exclusively 1,2,3-trisubstituted cis(1,2)/cis(2,3)-configured benzocyclopentenes by an electrophilic attack of the ylide on the olefinic double bond. This unsual transformation provides a convenient and direct method for the diastereoselective synthesis of functionalized bicyclo[3.3.0]octanes (characteristic structural units contained in polyquinane natural products), when cyclopentenes are used as cycloalkene partner.

Bis(2,2;6,6-tetramethyl-3,5-heptanedionato)cobalt(II) (Co(thd)(2)), a beta-diketonate prepared in a simple one-step procedure, is an excellent catalyst for aerobic epoxidation and Mukaiyama-Isayama hydroperoxysilylation of unactivated alkenes. For hydroperoxysilylation, Co(thd)(2) is superior to Co(acac)(2) and can catalyse oxidation of cyclic alkenes in excellent yield. Chiral beta-diketonate or keto iminato catalysts failed to catalyse this reaction in an enantioselective manner and a free radical mechanism consistent with this observation is proposed. Hydroperoxysilylation of cyclohex-1-enylmethanol by Co(thd)(2) followed by addition of a ketone/TsOH provides a simple one-pot procedure for the synthesis of spiro-1,2,4-trioxane antimalarials. (C) 2003 Published by Elsevier Ltd.

A thermal desorption particle beam mass spectrometer has been used to investigate the products and mechanisms of secondary organic aerosol formation from reactions of O3 with cyclohexene, cyclohept...

The H 2 O 2 -based epoxidation of bridged cyclic alkenes in a monophasic system containing low concentrations ( 4 n N] 4 [Pr 2 i NH 3 ] 2 H[P{Ti(O 2 )} 2 W 10 O 38 ]·H 2 O ( 1 ) (with two η 2 -peroxotitanium sites in the anion) has been studied in search of the catalytically active species involved. 31 P NMR spectra of 1 , measured under a variety of conditions, revealed that the active species was not hydroperoxotitanium complex [P{Ti(OOH)} 2 W 10 O 38 ] 7− or [P{Ti(OOH)}Ti(O 2 )W 10 O 38 ] 7− . The reaction pathways for the alkene epoxidation are discussed to understand the kinetics (especially the initial [H 2 O 2 ] dependence). It was concluded that the net catalytic reaction for the epoxidation occurred through the two-electron oxidation at the hydroperoxotitanium site in the catalyst.

[reaction: see text] Sultene 1 reacts with cyclic alkenes under mild Lewis acid catalysis to form thiiranes diastereoselectively. With 1-methoxycyclooctene as sulfur acceptor, an unexpected insertion product is formed, which provides valuable mechanistic insight into the sulfur-transfer process.

All presented reactions are performed with iodosylbenzene as well as iodylbenzene with the latter giving slightly higher yields of the desired products.

Pt/TiO2-catalyzed diborations of terminal and internal alkynes (I, IV and VI) as well as cyclic alkenes (XII) run in a stereoselective manner (cis-diboration).

A chemoenzymatic and selective method for the epoxidation of a series of linear and cyclic alkenes is described.

A mild and efficient protocol for the preparation of 1,2-dichloroalkane derivatives from olefins using NH4Cl and Oxone® at room temperature is described. A variety of terminal, internal, and cyclic alkenes reacted smoothly to give the corresponding dichlorinated products in good to excellent yields. Moreover, 1,2-disubstituted symmetrical and unsymmetrical olefins dichlorinated with moderate to excellent diastereoselectivity. This method precludes the use of acidic additives and transition metals in the synthesis of vicinal dichlorides.