V. I. Bykov

Synthesis of Z-isomeric insect sex pheromone components via ethenolysis of 1,5-cyclooctadiene

Abstract A novel syntheses of Z-5-decenol, Z-5-decenyl acetate, Z-7-dodecenol, Z-7-dodecenyl acetate, Z-9-tricosene, Z-7,8-epoxy-2-methyloctadecane which are sex pheromone components of Lepidoptera and Diptera orders, have been realized via stereoselective cometathesis of 1,5-cyclooctadiene with ethylene in the presence of MoCl 5 /SiO 2 -SnMe 4 as a key reaction. The main cometathesis product, 1,Z-5,9-decatriene, has been converted into pheromone components mentioned above by regioselective partial hydroboration or hydrozirconation with help of 9-BBN and Cp 2 ZrHCl, correspondingly. The protonolysis of the obtained zirconosene derivative gave 1,Z-5-decadiene. Hydroboration-oxidation or hydroboration-C 2 -homologation of the latter led to Z-5- or Z-7 monoene pheromone components. Hydroboration-iodination of terminal double bond in 1,Z-5,9-decatriene, and further cross-coupling of the obtained iodine derivative with convenient lithium cuprates resulted in Z-9-tricosene, the main sex pheromone component of House Fly ( Musca Domestica ), or in 2-methyl-Z-7-octadecene, the precursor of Gypsy Moth ( Lymantria Dispar ) sex attractant.

The olefin metathesis reaction : a versatile tool for fine organic synthesis

Abstract This study was devoted to the use of the metathesis reaction for the synthesis of alkenes containing various reactive structural fragments (strained rings, metal-carbon bonds, oxygen-containing functional groups). Among the W, Mo and Re catalysts studied Re2O7/Al2O3ue5f8PbEt4 and MoCl5/SiO2ue5f8SnMe4ue5f8SiCl4 turned out to be the most suitable. They were active toward a wide range of substrates bearing the fragments mentioned above, stable to catalyst poisons and able to be recovered. As a result, we accomplished the metathesis of alkylidene and alkenyl cycloalkanes, including 3- and 4-membered rings, which permitted us to develop a common method of synthesizing bi-and polycyclic hydrocarbons. The co-metathesis of cyclic C5-synthons results in the formation of isoprenoids and terpenoids. On the basis of co-metathesis with allylsilanes, a novel method for the lengthening of α-olefin chains and for double-bond transfer from the α to the β position has been demonstrated. Metathesis and co-metathesis reactions have been used to produce CH3(CH2)mCHue5fbCH(CH2)n X (where X = OAc, OH, CHO, m = 0–5, n = 4–10), which are used as insect pheromone components. Synthetic triglycerides formed by a co-metathesis reaction may be used for the production of various vegetable oil analogues.

Synthesis of natural compounds via the cycloolefin cometathesis with α-olefins

Cometathesis of cycloolefins with α-olefins has been studied in the presence of a MoCl 5 /SiO 2 -SnMe 4 catalyst. Three types of polyenes were observed in the products of this reaction: polyenes without any terminal double bond and those having one or two such bonds. It was shown that stereoselectivity of the cometathesis depends on cycloolefin ring size and reaction conditions. In some cases, the content of cis-isomers of I, A-dienes in final mixture reached 63-70%. The obtained polyenes were functionalized via a selective hydroboration of terminal double bonds. A technologically prospective strategy has been developed for the preparation of great variety of natural biologically active compounds (insect sex pheromones, growth regulators, fragrant composition components) on the basis of the cometathesis and hydroboration.

Synthesis of monoene pheromone components having a double bond in positions 6–11 using cometathesis of cycloolefins with α-olefins

Abstract Cometathesis of cycloolefins, 1, with linearα-alkenes, 2, using molybdenum pentachloride catalyst with a cocatalyst of tetramethyltin followed by hydroboration of the resulting α,ω-dienes 3 with 9-borabicyclo [3.3.1] nonane (9-BBN) and oxidation or carbonylation of the resulting boranes, 4, is a convenient route to Δ6–11 monoolefin derivatives.

Effect of the structure of coal-related model ethers on the rate and mechanism of their thermolysis: 1. Effect of the number of methylene groups in the R (CH2)nO(CH2)mR structure

Abstract The constants of thermolysis rate of C 6 H 5 ue5f8(CH 2 ) n ue5f8Oue5f8(CH 2 ) m ue5f8C 6 H 5 ethers were measured in conditions close to those of coal liquefaction (hydrogen pressure of 8.5 MPa; temperature up to 410 °C) but minimizing secondary conversions (i.e. in ten-fold excess of tetralin). The ethers form the following reactivity series depending on n and m values: at 350 ° C ue5f8[0,1] ⪢ [0,2] ⪢ [1,1] > [1,2] > [2,2] ⪢ [0,0], and at 410 ° C ue5f8 [0,1] ⪢ [0,2] > [1,2] > [1,1] > [2,2] ⪢ [0,0]. The mechanism and pathways of ether conversions were defined based on the changing concentrations of the intermediate and final reaction products. In the case of benzyl phenyl and dibenzyl ethers the thermolysis was accompanied by intramolecular rearrangements.

Effect of the structure of coal-related model ethers on the rate and mechanism of their thermolysis: 2. Effect of substituents in the C6H5CH2OC6H4X structure

Abstract The pathways of conversion were studied and the rate constants of thermolysis for meta - and para -substituted benzyl aryl ethers were measured under conditions close to the initial stages of coal liquefaction (hydrogen pressure, 8.5 MPa, 275–350 °C; solvent: tetralin). The destruction of ethers is accompanied by rearrangement into the corresponding derivatives of benzylphenol that amount to 20–25 % of the reaction products. The electron-donating substituents increase the thermolysis rate whereas the electron-accepting substituents decrease it. The effect of substituents on thermolysis rate is described by the Hammet equation with ϱ constant at 325 °C equal to −2.75.

A NEW SYNTHESIS OF (Z,E)-TETRADEC-11-ENYL ACETATE, THE SEX ATTRACTANT OF THE OMNIVOROUS LEAFROLLER (ARCHIPS PODANA)

A four-step synthesis of the title pheromone was elaborated starting from accessible (Z)-cyclooctene and but- 1-ene.

Photoluminescence of cadmium selenide quantum dots in polymer solutions

The effect of solvent on the photoluminescence of cadmium selenide quantum dots stabilized by oleic acid is examined with the example of two organic solvents: toluene and THF. It is found that THF favors desorption of ligands and formation of surface defects to a greater extent than toluene; as a result, the maximum of the photoluminescence band shifts to the red spectral region and its intensity decreases. The addition of polymers to the solution of quantum dots causes changes in the efficiency of photoluminescence and in the kinetics of its quenching. In the range of low concentrations (≤2 wt %) of quantum dots in polymer solutions, the intensity of luminescence first grows and then passes through a maximum and decreases. This effect may be explained both by the increasing number of surface defects and by quenching via energy transfer to polymers, especially in the case of polymers containing aromatic groups.

Binary and Ternary Catalytic Systems for Olefin Metathesis Based on MoCl 5 /SiO 2

Kinetics of α-olefin metathesis in the presence of binary (MoCl5/ SiO2-Me4Sn) and ternary catalytic systems (MoCl5/SiO2-Me4Sn-ECl4, E = Si or Ge) was studied. Specifically, kinetics and reactivity of 1-decene, 1-octene, and 1-hexene in the metathesis reaction at 27°C and 50°C in the presence of MoCl5/ SiO2-SnMe4 were examined and evaluated in detail. It was shown that experimental data comply well with the simple kinetic equation for the rate of formation of symmetrical olefins with allowance for the reverse reaction and catalyst deactivation: (r = left( {k_1 cdot c_alpha - k_{ - 1} cdot c_s } right) cdot e^{ - k_d cdot tilde n_{tot} } ). The coefficients for this equation were determined, and it was shown that these α-olefins had practically the same reactivity. It was found that reactivation in the course of metathesis took place due to the addition of a third component (silicon tetrachloride or germanium tetrachloride in combination with tetramethyltin) to a partially deactivated catalyst. The number of active centers was determined (5–6% of the amount of Mo) and the mechanisms of formation, deactivation, and reactivation were proposed for the binary and ternary catalytic systems. The role of individual components of the catalytic systems was revealed.

New synthesis of (Z)-5- and (Z)-7-monoene components of insect sex pheromones of the Lepidoptera order

A new procedure was developed for the synthesis of (Z)-5- and (Z)-7-monoene components of sex pheromones of Lepidoptera insects based on cometathesis of readily accessible cycloocta-1,5-diene and ethylene.