Double Bond Migration Research Articles

Colochiroside E, an Unusual Non-holostane Triterpene Sulfated Trioside from the Sea Cucumber Colochirus Robustus and Evidence of the Impossibility of a 7(8)-Double Bond Migration in Lanostane Derivatives having an 18(16)-Lactone

The unusual non-holostane triterpene glycoside, colochiroside E (1) was isolated from the sea cucumber Colochirus robustus (Cucumariidae, Dendrochirotida). The structure of 1 was established by analysis of 1D, 2D NMR and HRESI MS data. Colochiroside E (1) belongs to a rare group of glycosylated 9β-H-lanosta-18(16)-lactones and has an unprecedented sulfated trisaccharide carbohydrate chain consisting of two glucose and one xylose units. In contrast with (9β-H)-7(8)-unsaturated holostane glycosides, the 7(8)-double bond in the having (9β-H)-configuration aglycone of colochiroside E is not capable of migration into the 8(9)- and then into the 9(11)-position on treatment with HCl. The formation of a chlorine derivative of 1 was observed under these conditions.

Total synthesis of dysidavarone A

Dysidavarone A is a sesquiterpene isolated from the South China Sea sponge Dysidea avara and was reported that it showed significant anticancer activities. Because the compound has unique ‘dysidavarane’ carbon skeleton and potent biological activity, a seven-step stereoselective synthesis of dysidavarone A was developed. The key steps of the synthesis involved stereoselective reductive-alkylation, intramolecular α-arylation and double bond migration reaction. The anti-proliferation activities of Dysidavarone A against human kidney carcinoma cell lines 786-O and human prostate cancer cell lines PC-3 were also assessed.

SYNTHETIC TRANSFORMATIONS OF SESQUITERPENE LACTONES. 9. SYNTHESIS OF 13-(PYRIDINYL)EUDESMANOLIDES

The reaction of isoalantolactone, a sesquiterpene α-methylidene-γ-lactone, with bromo(iodo)pyridines under the Heck reaction conditions gave 3-(pyridylmethylidene)-8а-methyldecahydronaphtho[2,3- b ]furan-2(3 Н )-ones and 3-(pyridylmethyl)-8а-methyloctahydronaphtho[2,3- b ]furan-2(4 Н )-ones, products of double bond migration. The yield and product ratio depended on the reaction conditions and the nature of halopyridine. The effectiveness of Pd(OAc) 2 –caffeine catalytic system was demonstrated in this reaction. How to Cite Patrushev, S. S.; Shakirov, M. M.; Shults, E. E. Chem. Heterocycl. Compd. 2016 , 52 , 165. [ Khim. Geterotsikl. Soedin. 2016 , 52 , 165.] For this article in the English edition see DOI 10.1007/s10593-016-1855-1

Raman and nuclear magnetic resonance investigation of alkali metal vapor interaction with alkene-based anti-relaxation coating.

The use of anti-relaxation coatings in alkali vapor cells yields substantial performance improvements compared to a bare glass surface by reducing the probability of spin relaxation in wall collisions by several orders of magnitude. Some of the most effective anti-relaxation coating materials are alpha-olefins, which (as in the case of more traditional paraffin coatings) must undergo a curing period after cell manufacturing in order to achieve the desired behavior. Until now, however, it has been unclear what physicochemical processes occur during cell curing, and how they may affect relevant cell properties. We present the results of nondestructive Raman-spectroscopy and magnetic-resonance investigations of the influence of alkali metal vapor (Cs or K) on an alpha-olefin, 1-nonadecene coating the inner surface of a glass cell. It was found that during the curing process, the alkali metal catalyzes migration of the carbon-carbon double bond, yielding a mixture of cis- and trans-2-nonadecene.

Synthetic transformations of sesquiterpene lactones 9.* Synthesis of 13-(pyridinyl)eudesmanolides

The reaction of isoalantolactone, a sesquiterpene α-methylidene-γ-lactone, with bromo(iodo)pyridines under the Heck reaction conditions gave 3-(pyridylmethylidene)-8а-methyldecahydronaphtho[2,3-b]furan-2(3Н)-ones and 3-(pyridylmethyl)-8а-methyloctahydronaphtho[2,3-b]-furan-2(4Н)-ones, products of double bond migration. The yield and product ratio depended on the reaction conditions and the nature of halopyridine. The effectiveness of Pd(OAc)2–caffeine catalytic system was demonstrated in this reaction.

Cu(NHC)]-Catalyzed C-H Allylation and Alkenylation of both Electron-Deficient and Electron-Rich (Hetero)arenes with Allyl Halides.

New reactivity of a [Cu(NHC)] (NHC=N-heterocyclic carbene) catalyst is disclosed for the efficient C-H allylation of polyfluoroarenes using allyl halides in benzene at room temperature. The same catalyst system also promotes an isomerization-induced alkenylation of initially the generated allyl arenes when the reaction is run in tetrahydrofuran. Significantly, not only electron-deficient but also electron-rich (hetero)arenes undergo this double-bond migration process, thus leading to alkenylated products. The present system features mild reaction conditions, broad scope with respect to the arene substrates and allyl halide reactants, good functional-group tolerance, and high stereoselectivity.

Titanium and Zirconium Hydride-Catalyzed Regioselective Isomerization of 1,4-Dihydrofulvenes: Access to 1-Substituted 1,2-Dihydrofulvenes.

Zirconium hydride-catalyzed C═C double bond migration from nonconjugated to conjugated dienes is described. Applied to 1-substituted 1,4-dihydrofulvenes, the migration leads selectively to 1-substituted 1,2-dihydrofulvenes. The C═C double bond migration can also be catalyzed by titanium hydride, allowing a one-pot procedure to provide 1-substituted 1,2-dihydrofulvenes from pentafulvenes via two titanium-catalyzed steps. This sequence was proven to be temperature-dependent, allowing the selective access to a conjugated or nonconjugated adduct by a simple temperature tuning. The synthetic potential of the methodology was illustrated by the diastereoselective synthesis of a polyhydroxycyclopentane.

ChemInform Abstract: Synthesis of Polysubstituted γ‐Butenolides via a Radical Pathway: Cyclization of α‐Bromo Aluminium Acetals and Comparison with the Cyclization of α‐Bromoesters at High Temperature.

AbstractA four‐step one‐pot procedure involving generation of α‐bromo aluminum acetals, their subsequent radical cyclization followed by oxidation of the resulting cyclic aluminum acetals and base promoted double bond migration is developed to convert α‐bromoesters derived from propargylic alcohols to butenolides.

ChemInform Abstract: ′Syn‐effect′ in the Diastereoselective Alkylation of 3‐[(E)‐α,β‐Unsaturated‐γ‐substituted] ‐N‐acyloxazolidinones.

Abstract Synthetic methods for the formation of alkenes usually produce the E-alkene because it is more stable. However, in isomerization reaction (double bond migration) that takes place in α, β−unsaturated carbonyl compounds, when these carbonyl compounds are exposed to strong bases, furnish Z-alkenes highly stereoselective depending on the γ-substituent in the α, β-unsaturated carbonyl. This stereoselectivity can be attributed to the known Syn-effect. The synthetic value of this methodology is the achievement of chiral alcohol bearing an electron rich Z-alkene, as well as substituted, which was accomplished via removal of the oxazolidinone moiety under treatment with NaBH4, THF-H2O.

ChemInform Abstract: Substrate Activation in the Catalytic Asymmetric Hydrogenation of N‐Heteroarenes

AbstractReview: [50 refs.

ChemInform Abstract: Copper‐Catalyzed Trifluoromethylation of Trisubstituted Allylic and Homoallylic Alcohols.

An efficient copper-catalyzed trifluoromethylation of trisubstituted allylic and homoallylic alcohols with Togni's reagent has been developed. This strategy, accompanied by a double-bond migration, leads to various branched CF3-substituted alcohols by using readily available trisubstituted cyclic/acyclic alcohols as substrates. Moreover, for alcohols in which β-H elimination is prohibited, CF3-containing oxetanes are isolated as the sole product.

Late stage Fe(CO)5 promoted double bond migration: total synthesis of limazepines C and D

The first total syntheses of limazepines C and D were accomplished from inexpensive and readily available starting materials using an iron pentacarbonyl promoted allylamide–enamide double bond migration as a key step. The obtained limazepine C was found to be unstable and undergoes oxidation to limazepine D.

Theoretical study on the activity of hydrogen atom of imidazolium ring in ionic liquids

The double-bond isomerization of 1-pentene catalyzed by [Emim]BF4 ionic liquid and the interaction relationship of the [Emim]BF4 ion pair have been studied by using density functional theory (DFT) at the B3LYP/6-31G(d,p) level. The obtained results reveal that the [Emim]+ and BF4− ions exist in the form of the ion pairs in the ionic liquid system, and only two stable structures are obtained. The isomerization process of 1-pentene on [Emim]BF4 ionic liquids proceeds via a concerted reaction pathway. The hydrogen atom transfer is accompanied by the migration of the intramolecular double bond. The ionic liquid acts as a proton donor, while it also favors the proton abstraction. The adsorption energies of 1-pentene on the 2-position and 4-position hydrogen atoms of the imidazolium ring are −11.32 and −7.42kJ/mol, respectively. The apparent activation energies of the double-bond isomerization for 2-position hydrogen atom and 4-position hydrogen atom are 196.91 and 214.64kJ/mol, respectively. Those indicate that two kinds of hydrogen atoms of the imidazolium ring have both catalytic activities, but the activity of 2-position hydrogen atom is much higher than the one of 4-position hydrogen atom.

Can density cumulant functional theory describe static correlation effects?

We evaluate the performance of density cumulant functional theory (DCT) for capturing static correlation effects. In particular, we examine systems with significant multideterminant character of the electronic wave function, such as the beryllium dimer, diatomic carbon, m-benzyne, 2,6-pyridyne, twisted ethylene, as well as the barrier for double-bond migration in cyclobutadiene. We compute molecular properties of these systems using the ODC-12 and DC-12 variants of DCT and compare these results to multireference configuration interaction and multireference coupled-cluster theories, as well as single-reference coupled-cluster theory with single, double (CCSD), and perturbative triple excitations [CCSD(T)]. For all systems the DCT methods show intermediate performance between that of CCSD and CCSD(T), with significant improvement over the former method. In particular, for the beryllium dimer, m-benzyne, and 2,6-pyridyne, the ODC-12 method along with CCSD(T) correctly predict the global minimum structures, while CCSD predictions fail qualitatively, underestimating the multireference effects. Our results suggest that the DC-12 and ODC-12 methods are capable of describing emerging static correlation effects but should be used cautiously when highly accurate results are required. Conveniently, the appearance of multireference effects in DCT can be diagnosed by analyzing the DCT natural orbital occupations, which are readily available at the end of the energy computation.

Cobalt‐Catalyzed Dual Annulation of o‐Halobenzaldimine with Alkyne: A Powerful Route toward Bioactive Indenoisoquinolinones

A cobalt-catalyzed dual annulation reaction for the synthesis of variously substituted indenoisoquinolinones from 2-bromobenzaldehydes, amines, and methyl 2-(ethynyl)benzoates has been developed. This method could also be applied to the synthesis of an array of highly functionalized bioactive indenoisoquinolinones and their derivatives. A possible mechanism of the cobalt catalysis is proposed, involving imine formation from bromobenzaldehyde and the amine, followed by a series of oxidative addition, alkyne insertion, cyclization reactions, and carbon-carbon double-bond migration. The regioselective alkyne insertion plays an important role for the success of the second annulation.

‘Syn-effect’ in the diastereoselective alkylation of 3-[(E)-α,β-unsaturated-γ-substituted]-N-acyloxazolidinones

Synthetic methods for the formation of alkenes usually produce the E-alkene because it is more stable. However, in isomerization reaction (double bond migration) that takes place in α, β−unsaturated carbonyl compounds, when these carbonyl compounds are exposed to strong bases, furnish Z-alkenes highly stereoselective depending on the γ-substituent in the α, β-unsaturated carbonyl. This stereoselectivity can be attributed to the known Syn-effect. The synthetic value of this methodology is the achievement of chiral alcohol bearing an electron rich Z-alkene, as well as substituted, which was accomplished via removal of the oxazolidinone moiety under treatment with NaBH4, THF-H2O.

ChemInform Abstract: Phosphonium Salt Induced Stereoselective Allylic Rearrangement During Chlorination of α‐Hydroxyallylphosphinates.

α-Hydroxyallylphosphinates were stereoselectively converted to γ-chloro allylphosphinates when treated with Ph3P and CCl4, via substitution of hydroxyl and migration of double bond. The reaction was promoted by phosphonium cation that acted as Lewis acid.

Copper-catalyzed trifluoromethylation of trisubstituted allylic and homoallylic alcohols.

An efficient copper-catalyzed trifluoromethylation of trisubstituted allylic and homoallylic alcohols with Togni's reagent has been developed. This strategy, accompanied by a double-bond migration, leads to various branched CF3-substituted alcohols by using readily available trisubstituted cyclic/acyclic alcohols as substrates. Moreover, for alcohols in which β-H elimination is prohibited, CF3-containing oxetanes are isolated as the sole product.

Multifaceted strategy for the synthesis of diverse 2,2'-bithiophene derivatives.

New catalytically or high pressure activated reactions and routes, including coupling, double bond migration in allylic systems, and various types of cycloaddition and dihydroamination have been used for the synthesis of novel bithiophene derivatives. Thanks to the abovementioned reactions and routes combined with non-catalytic ones, new acetylene, butadiyne, isoxazole, 1,2,3-triazole, pyrrole, benzene, and fluoranthene derivatives with one, two or six bithiophenyl moieties have been obtained. Basic sources of crucial substrates which include bithiophene motif for catalytic reactions were 2,2'-bithiophene, gaseous acetylene and 1,3-butadiyne.

Mealybug mating disruption by a sex pheromone derived from lavender essential oil

A characteristic constituent of lavender essential oils, lavandulol (2-isopropenyl-5-methyl-4-hexen-1-ol), and its relatives have been frequently discovered in the pheromones of mealybugs. Synthetic pheromones to interfere with their mate-finding communication are a potential management tool for these pests. The sex pheromone of the Japanese mealybug (Planococcus kraunhiae) is 2-isopropyliden-5-methyl-4-hexen-1-yl butyrate (isolavandulyl butyrate), and its alcohol moiety can easily be synthesized from lavandulol by means of acid-promoted double-bond migration. In this study, we synthesized isolavandulyl butyrate from natural lavandulol without isolating it from lavender essential oil. The resulting oil included both the pheromone and insect repellants, and the oil’s attractiveness was inferior to that of pure synthetic pheromone. However, the lavender oil-derived pheromone displayed a copulation-interference performance equivalent to that of the pure pheromone when large amounts were released around mealybug colonies. This study proposes a unique strategy for mealybug management using the pheromone derived from lavender essential oil.