Gas-phase rate coefficients for the reactions of nitrate radicals with (Z)-pent-2-ene, (E)-pent-2-ene, (Z)-hex-2-ene, (E)-hex-2-ene, (Z)-hex-3-ene, (E)-hex-3-ene and (E)-3-methylpent-2-ene at room temperature

Rate coefficients for reactions of nitrate radicals (NO3) with (Z)-pent-2-ene, (E)-pent-2-ene, (Z)-hex-2-ene, (E)-hex-2-ene, (Z)-hex-3-ene, (E)-hex-3-ene and (E)-3-methylpent-2-ene were determined to be (6.55 +/- 0.78)x 10(-13) cm3 molecule(-1) s(-1), (3.78 +/- 0.45)x 10(-13) cm3 molecule(-1) s(-1), (5.30 +/- 0.73)x 10(-13) cm(3) molecule(-1) s(-1), (3.83 +/- 0.47)x 10(-13) cm(3) molecule(-1) s(-1), (4.37 +/- 0.49)x 10(-13) cm(3) molecule(-1) s(-1), (3.61 +/- 0.40)x 10(-13) cm3 molecule(-1) s(-1) and (8.9 +/- 1.5)x 10(-12) cm3 molecule(-1) s(-1), respectively. We performed kinetic experiments at room temperature and atmospheric pressure using a relative-rate technique with GC-FID analysis. The experimental results demonstrate a surprisingly large cis-trans(Z-E) effect, particularly in the case of the pent-2-enes, where the ratio of rate coefficients is ca. 1.7. Rate coefficients are discussed in terms of electronic and steric influences, and our results give some insight into the effects of chain length and position of the double bond on the reaction of NO3 with unsaturated hydrocarbons. Atmospheric lifetimes were calculated with respect to important oxidants in the troposphere for the alkenes studied, and NO3-initiated oxidation is found to be the dominant degradation route for (Z)-pent-2-ene, (Z)-hex-3-ene and (E)-3-methylpent-2-ene.     

(5R,6R)-6-苯基-5-(苯磺酰基乙酰基)二环[2.2.1]-2-庚烯的合成及结构表征

报道了一种制备4-苯基-1-苯磺酰基-3-丁烯-2-酮的新合成方法. 4-苯基-3-丁烯-2-酮与溴化试剂Ph₃P^＋CH₂CH₂- COOHBr 作用, 得到1-溴-4-苯基-3-丁烯-2-酮, 不经分离直接与苯亚磺酸钠发生亲核取代反应, 得到4-苯基-1-苯磺酰基-3-丁烯-2-酮. 将此反应产物作为亲双烯体与环戊二烯在手性钛金属催化剂催化下进行不对称Diels-Alder反应, 得到了＞99% ee 的环加成产物(5R,6R)-6-苯基-5-(苯磺酰基乙酰基)二环[2.2.1]-2-庚烯. 用X衍射法对产物的晶体结构进行了测定, 讨论了反应机理, 通过元素分析, NMR, MS对产物的结构进行了表征.     

Reduction of 3-(2-hydroxyethyl)-1,5-dinitro-3-azabicyclo[3.3.1]non-6-ene

Reduction of the nitro groups in 3-(2-hydroxyethyl)-1,5-dinitro-3-azabicyclo[3.3.1]non-6-ene was studied. The structures of the reaction products were confirmed using ¹H and ¹³C NMR spectroscopy.     

Metathesis of hex-1-ene in ionic liquids catalyzed by WCl6

Metathesis of hex-1-ene in ionic liquids catalyzed by WCl₆ was studied. The metathesis is preceded by isomerization of hex-1-ene to hex-2-ene, from which the main reaction product, viz., oct-4-ene, is derived. The WCl₆-1-butyl-3-methylimidazolium tetrafluoroborate (BMIM·BF₄) system efficiently catalyzes metathesis of linear olefin, the ionic liquid serving as the reaction medium by forming a stable homogeneous catalytic system with WCl₆. The yields of the metathesis products increase with increasing reaction temperature. The addition of tin-containing promoters leads to a substantial increase in the reaction rate. In the WCl₆-BMIM·BF₄-SnBu₄ system, the selectivity of the formation of oct-4-ene is significantly enhanced.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2094–2097, October, 2004.     

Synthetic studies on arene-olefin cycloadditions-VIII. Total syntheses of (±)-silphiperfol-6-ene, (±)-7 α H-silphiperfol-5-ene and (±)-7 β H-silphiperfol-5-ene

Total syntheses of (±)-silphiperfol-6-ene, (±)-7 α H-silphiperfol-5-ene and (±)-7 β H-silphiperfol-5-ene are described in which a new element of stereoinduction in arene-olefin meta cycloadditions was tested and a new method for cycloadduct transformation was developed.     

6-烯-8-羰基-1-叔丁氧基羰基氮杂螺[4,4]壬烷的合成

以烯丙基脯氨酸甲酯(1)为起始原料, 经7步反应以42%的总收率得到了三尖杉碱合成中的重要中间体6-烯-8-羰基-1-叔丁氧基羰基氮杂螺[4,4]壬烷(7). 关键反应为构筑螺环季碳的[2,3]斯蒂文森重排(Stevens rearrangement)及烯丙基双键加氧的酸内酯化反应(Acid-lactonization reaction).     

Reaction of hexadecafluorobicyclo[4.4.0]dec-1(6)-ene with diethylamine

The spectral characteristics of products formed in the reaction of an incompletely fluorinated impurity in perfluorodecalin, hexadecafluorobicyclo[4.4.0]dec-1(6)-ene, with amines in various solvents were studied. The reaction rates in various solvents were compared, and the distribution of the reaction products between perfluorodecalin and solvents was examined.     

Total synthesis of (+/-)-hapalindole Q

[reaction: see text] The total synthesis of the antibacterial and antimycotic alkaloid hapalindole Q has been achieved in eight steps and 12.4% overall yield. The key step involves a regio- and diastereoselective Diels-Alder reaction to afford a bicyclo[2.2.2]oct-2-ene. This cycloadduct was subsequently dihydroxylated, cleaved, and converted to the natural product.     

Synthesis and chemical properties of 8-aryl-7-acyl-1-6-dimethyl-6-hydroxy-4-cyano-5,6,7,8-tetrahydro-3(2H)-isoquinolinones and isoquinolinethiones

8-Aryl-7-acetyl-1, 6-dimethyl-6-hydroxy-4-cyano-5, 6, 7, 8-tetrahydro-3(2H)-isoquinolinones and -isoquinolinethiones and their sodium salts were obtained by the reaction of cyanoacetamide and cyanothioacetamide with 3-aryl-2, 4-diacetyl-5-methyl-5-hydroxycyclohexanonesinbasicrnedium. 8-Aryl-7-acetyl-6-methoxycarbonyl-1, 6-dimethyl-4-cyano-5, 6, 7, 8-tetrahydro-3(2H)-isoquinolinones were obtained by the reaction of acetyl chloride and the above isoquinolinone sodium salts. The reaction of iodoacetamide and the above isoquinolinethione sodium salts yielded 8-aryl-7-acetyl-3-carbamoylmethylthio-1, 6-dimethyl-4-cyano-5, 6, 7, 8-tetra-hydroisoquinolines, which were cyclized into 1-amino-6-aryl-7-acetyl-2-carbamoyl-5, 8-dimethyl-8-hydroxy-6, 7, 8, 9-tetrahydrothiophene[2,3-c]isoquinolines in basic medium.     

Synthesis of 2,4-dimethyl-3-acetyl-l,6-dioxaspiro[4,4]non-2-ene

Conclusions A synthesis is reported for 2,4-dimethyl-3-acetyl-1,6-dioxaspiro[4,4]nan-2-ene, which is the first example of a trisubstituted spiroketal.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 209–210, January, 1985.     

Synthesis and reactions of 3-acetyl-6-methyl-2-(methylthio)pyridine

A reaction of methyllithium with 3-cyano-6-methylpyridine-2(1 H)-thione followed by alkylation of the resulting 3-acetylpyridinethione, or a direct reaction of methyllithium with 3-cyano-6-methyl-2-(methylthio)pyridine, afforded 3-acetyl-6-methyl-2-(methylthio)pyridine. The ketone obtained was examined in bromination reactions under various conditions. Bromi-nation in methanol or chloroform, proceeding through the formation of sulfonium bromides, gave substituted 3-(bromoacetyl)pyridine. A reaction of 3-acetyl-6-methyl-2-(methyl-thio)pyridine with N-bromosuccinimide in CCl4 afforded N-(pyridinesulfenyl)succinimide. The bromo ketone was used for the synthesis of various heterocyclic compounds.     

Orbital control of stereochemistry in acid-catalysed addition reactions of endo -tricyclo[3.2.1.02,4]0ct-6-ene

The reaction of endo-tricyclo[3.2.1.0^2,4]oct-6-ene 1 with methanol in the presence of catalytic amounts of toluene-p-sulphonic acid has been shown to give 2-exo- and endo-methoxybicyclo[3.2.1]oct-3-ene (2c) and (2d) and 2-endo-methoxybicyclo[3.2.1]oct-6-ene (13). The formation of 2-exo- methoxybicyclo[3.2.1]oct-3-ene (2c), the major product of reaction, has been probed by deuterium labelling experiments and a series of 6-exo-7-exo- dideuterobicyclo[3.2.1]oct-3-enes synthesised for ²H, ¹H and ¹³C NMR spectral analysis in order unambiguously to determine the stereochemistry of proton attack on endo-tricyclo[3.2.1 0^2,4]oct-6-ene (1). The formation of 2-exo-methoxybicyclo[3.2.1]oct-3-ene (2c) has been determined to involve corner protonation of the cyclopropyl moiety and skeletal rearrangement to an allylic cation with a small but measurable memory effect     

Synthesis and properties of 5-(1,2-dihaloethyl)-2′-deoxyuridines and related analogues

The regiospecific reaction of 5-vinyl-3′,5′-di-O-acetyl-2′-deoxyuridine ( 2 ) with HOX (X = Cl, Br, I) yielded the corresponding 5-(1-hydroxy-2-haloethyl)-3′,5′-di-O-acetyl-2′-deoxyuridines 3a-c . Alternatively, reaction of 2 with iodine monochloride in aqueous acetonitrile also afforded 5-(1-hydroxy-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3c ). Treatment of 5-(1-hydroxy-2-chloroethyl)- ( 3a ) and 5-(1-hydroxy-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3b ) with DAST (Et₂NSF₃) in methylene chloride at -40° gave the respective 5-(1-fluoro-2-chloroethyl)- ( 6a , 74%) and 5-(1-fluoro-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6b , 65%). In contrast, 5-(1-fluoro-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6e ) could not be isolated due to its facile reaction with methanol, ethanol or water to yield the corresponding 5-(1-methoxy-2-iodoethyl)- ( 6c ), 5-(1-ethoxy-2-iodoethyl)- ( 6d ) and 5-(1-hydroxy-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3c ). Treatment of 5-(1-hydroxy-2-chloroethyl)- ( 3a ) and 5-(1-hydroxy-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3b ) with thionyl chloride yielded the respective 5-(1,2-dichloroethyl)- ( 6f , 85%) and 5-(1-chloro-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6g , 50%), whereas a similar reaction employing the 5-(1-hydroxy-2-iodoethyl)- compound 3c afforded 5-(1-methoxy-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6c ), possibly via the unstable 5-(1-chloro-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine intermediate 6h . The 5-(1-bromo-2-chloroethyl)- ( 6i ) and 5-(1,2-dibromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6j ) could not be isolated due to their facile conversion to the corresponding 5-(1-ethoxy-2-chloroethyl)- ( 6k ) and 5-(1-ethoxy-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 61 ). Reaction of 5-(1-hydroxy-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3b ) with methanolic ammonia, to remove the 3′,5′-di-O-acetyl groups, gave 2,3-dihydro-3-hydroxy-5-(2′-deoxy-β-D-ribofuranosyl)-furano[2,3-d]pyrimidine-6(5H)-one ( 8 ). In contrast, a similar reaction of 5-(1-fluoro-2-chloroethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6a ) yielded (E)-5-(2-chlorovinyl)-2′-deoxyuridine ( 1b , 23%) and 5-(2′-deoxy-β-D-ribofuranosyl)furano[2,3-d]pyrimidin-6(5H)-one ( 9 , 13%). The mechanisms of the substitution and elimination reactions observed for these 5-(1,2-dihaloethyl)-3′,5′-di-O-acetyl-2′-deoxyuridines are described.     

Diastereoselective synthesis of (+/-)-(3-aminocyclopentane)alkylphosphinic acids, conformationally restricted analogues of GABA

A divergent synthesis of both diastereoisomers of (+/-)-(3-aminocyclopentane)alkylphosphinic acid is described. Both diastereoisomers are obtained in 5 steps from the key (+/-)-(3-hydroxycyclopent-1-ene)alkylphosphinate esters which are prepared via a palladium catalysed C-P bond forming reaction.     

Reactions of chloromethoxy-substituted 3-(2-acetoxyethyl)-1-hydroxytriaz-1-ene 2-oxides with 1-alkoxy-3-(2-hydroxyethyl)triaz-1-ene 2-oxide alkali salts

Reactions of 1-alkoxy-3-(2-hydroxyethyl)triaz-1-ene 2-oxides and 1-chloromethoxytriaz1-ene 2-oxides with chloromethoxy derivatives of 3-alkyl-3-(2-acetoxyethyl)- and 3,3-bis(2-acetoxyethyl)-1-hydroxytriaz-1-ene 2-oxides result in very complex product mixtures with the major product comprising the starting salt fragments linked by a methylene bridge. In these products, the central methylene group bridges either two oxygen atoms or two nitrogen atoms, or one oxygen and one nitrogen atom. The synthesized compounds contain from two to four 2-hydroxyethyl moieties.     

Thermal isomerization of tricyclo[4.1.0.0(2,7)]heptane and bicyclo[3.2.0]hept-6-ene through the (E,Z)-1,3-cycloheptadiene intermediate

The thermal isomerization of tricyclo[4.1.0.0(2,7)]heptane and bicyclo[3.2.0]hept-6-ene was studied using ab initio methods at the multiconfiguration self-consistent field level. The lowest-energy pathway for thermolysis of both structures proceeds through the (E,Z)-1,3-cycloheptadiene intermediate. Ten transition states were located, which connect these three structures to the final product, (Z,Z)-1,3-cycloheptadiene. Three reaction channels were investigated, which included the conrotatory and disrotatory ring opening of tricyclo[4.1.0.0(2,7)]heptane and bicyclo[3.2.0]hept-6-ene and trans double bond rotation of (E,Z)-1,3-cycloheptadiene. The activation barrier for the conrotatory ring opening of tricyclo[4.1.0.0(2,7)]heptane to (E,Z)-1,3-cycloheptadiene was found to be 40 kcal mol(-1), while the disrotatory pathway to (Z,Z)-1,3-cyclohetpadiene was calculated to be 55 kcal mol(-1). The thermolysis of bicyclo[3.2.0]hept-6-ene via a conrotatory pathway to (E,Z)-1,3-cycloheptadiene had a 35 kcal mol(-1) barrier, while the disrotatory pathway to (Z,Z)-1,3-cyclohetpadiene had a barrier of 48 kcal mol(-1). The barrier for the isomerization of (E,Z)-1,3-cycloheptadiene to bicyclo[3.2.0]hept-6-ene was found to be 12 kcal mol(-1), while that directly to (Z,Z)-1,3-cycloheptadiene was 20 kcal mol(-1).     

Oxymercuration-demercuration of car-3-ene

The composition of the products of the oxymercuration-demercuration reaction of car-3-ene according to the degree of its transformation has been studied. It has been established that this reaction forms trans-caran-3-ol, α-terpineol, m-menth-6-en-8-ol, 3,4-epoxy-trans-carane, p- and m-1, 8-cineoles, p- and m-1,8-terpins, and terpene esters. It has been shown that the double bond of car-3-ene possesses a higher reactivity than the cyclopropane ring, and the opening of the latter takes place equally at both external bonds.     

Acylation of fluorine-containing spiro[cyclopropane-1-pyrazolines] and dehydrohalogenation of the resulting adducts

Acylation of 6-(1-fluorovinyl)-6-methyl- and 6-(2,2,3,3-tetrafluorocyclobutyl)-4,5-diazaspiro[2.4]hept-4-enes with acetyl chloride proceeds as electrophilic addition to the N(5) atom and is accompanied by opening of the cyclopropane ring to give 1-acetyl-3-(2-chloroethyl)-5-(1-fluorovinyl)-5-methyl- and 1-acetyl-3-(2-chloroethyl)-5-(2,2,3,3-tetrafluorocyclobutyl)-4,5-dihydropyrazoles, respectively. Under the same conditions, acylation of 6-(2,3,3-trifluorocyclobut-1-enyl)-4,5-diazaspiro[2.4]hept-4-ene is not regioselective. The (2-chloroethyl) pyrazolines obtained undergo dehydrochlorination into vinylpyrazolines in the presence of an excess of MeONa in MeOH. The reaction of 4-acetyl-6-(2,3,3-trifluorocyclobut-1-enyl)-4,5-diazaspiro[2.4]hept-5-ene with MeONa results in selective replacement of the F atom at the double bond by a methoxy group.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 419–422, February, 2005.     

Synthesis of 11-aminodrim-7-ene from drimenol

11-Aminodrim-7-ene was synthesized from drimenol in four steps. Drimenol was oxidized into drimenal and its oxime was dehydrated by p-tosylchloride or acetic anhydride in pyridine to form 9-cyano-11-nordrim-7-ene, reduction of which by LiAlH₄ in the presence of anhydrous AlCl₃ produced 11-aminodrim-7-ene. The reaction of 9-cyano-11-nordrim-7-ene, NaBH₄, and CoCl₂·6H₂O produced a mixture of drimenylamine and 7,8-dihydrodrimenylamine in a 2:1 ratio. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 311–314, May–June, 2009.     

Thermal isomerization of cis,anti,cis-tricyclo[6.3.0.0(2,7)]undec-3-ene to endo-tricyclo[5.2.2.0(2,6)]undec-8-ene

[reaction: see text] The gas-phase thermal isomerization of cis,anti,cis-tricyclo[6.3.0.0(2,7)]undec-3-ene (1) to endo-tricyclo[5.2.2.0(2,6)]undec-8-ene (2) at 315 degrees C occurs cleanly through a symmetry-forbidden [1,3] suprafacial,retention (sr) pathway.