卡宾与2-丁烯环加成反应机理的MNDO法研究

用MNDO法研究单线态和三线态卡宾与乙烯,顺式及反式-2-丁烯的反应途径。合理地解释了顺式和反式-2-丁烯与三线态卡宾都形成顺式和反式-2-二甲基环丙烷。用MNDOCI计算了有关反应的反应活化能。     

反式2,3-二芳基取代-1-氨基环丙烷羧酸的合成及其结构研究

芳香醛与马尿酸在Erlenmeyer反应条件下缩合得到(Z)-2-苯基4芳亚甲基-5(4H)-噁唑酮,然后在室温下与芳基重氮甲烷通过非对映高立体选择性1,3-偶极环加成反应得到螺环化合物,再经醇解开环、水解去保护合成出反式2,3-二芳基-1-氨基取代环丙烷羧酸．通过元素分析,IR,^1H NMR,^13C NMR,MS和X射线晶体测定,确认了它们的化学结构和立体构型．实验结果表明,通过选择适当的芳香醛和芳基重氮甲烷,可以得到不同立体构型的反式2,3-二芳基取代-1-氨基环丙烷羧酸．     

1-(2, 6, 6-三甲基-1-环己烯基-)-3-甲基-2-丁烯-4-醛合成新工艺

1-(2; 6; 6-三甲基-1-环己烯基-)-3-甲基-2-丁烯-4-醛合成新工艺;(三甲基环己烯基)甲基丁烯醛;卡宾反应; β-紫罗兰酮;三甲基溴化硫     

(S)-(+)-2,2-二甲基环丙烷甲酰胺的不对称合成

以环己二胺作为手性源,与3,5-二叔丁基水杨醛经缩合反应制得Salen配体(R,R)-N,N'-二(3,5-二叔丁基水杨醛)-1,2-环己二胺(6);甘氨酸乙酯盐酸盐经重氮化和6与三氟甲烷磺酸亚铜催化的不对称环丙烷化反应制得(S)-(+)-2,2-二甲基环丙烷甲酸乙酯(9);9经水解、酰氯化和氨解反应合成了(S)-(+)-2,2-二甲基环丙烷甲酰胺,ee值82%,总收率55.4%,其结构经1H NMR和IR确证。     

低价钛盐还原反应的研究——Ⅲ.2,2-二芳基-1,1,1-三氯乙烷与低价钛盐的反应

2,2-二芳基-1,1,1-三氯乙烷(1)与TiCl₄-Zn起脱氯还原重排反应生成1,2-二芳基乙烯(3)。与TiCl₄-Mg反应时,2,2-二(对甲苯基)-1,1,1-三氯乙烷和2,2-二(对乙氧苯基)-1,1,1-三氯乙烷(1c,1d)主要得到重排产物2,2-二芳基乙烯(3)和2,2-二芳基-1-氯乙烯(4),后者可能是由相应的2,2-二芳基-1,1-二氯乙烷(2)生成的。但2,2-二苯-1,1,1-三氯乙烷和2,2-二(对氯苯基)-1,1,1-三氯乙烷(1a,1b)与此试剂反应只生成还原产物2,2-二芳基-1,1-二氯乙烷(2a,2b)。     

环丙烷甲酸-2-萘甲酯(杀螨剂)的合成

采用一种新的方法合成了环丙烷甲酸-2-萘甲酯。这种杀螨剂的合成过程为, 在碱、季胺型TOMAC相转移催化作用下, 1,2-二溴乙烷与丙二酸二乙酯反应合成1,1-环丙烷二羧酸, 然后脱羧, 得到环丙烷甲酸, 再制成环丙烷甲酸钠, 在Bu~4NBr(TBAB)季胺型相转移催化作用下, 与2-(溴甲基)萘合成得环丙烷甲酸-2-萘甲酯。其总产率为12.9％, 纯度为95.5％。初步证明对螨类害虫─柑桔红蜘蛛有效。     

双(烯基环戊二烯基)IVB族金属衍生物的研究

本文用烯丙基、丁烯-2-基环戊二烯基钠与IVB族金属氯化物反应,合成了新的双(烯丙基环戊二烯基)和双(丁烯-2-基环戊二烯基)二氯化钛、锆、铪.利用卤素交换或与芳基锂、硫氰酸钾、硫化氢反应制得双(烯基环戊二烯基)二卤、二芳基、二硫氰基和二巯基金属衍生物.考察了双(烯丙基环戊二烯基)二卤化钛、锆和铪中烯丙基与卤化氢、卤素的加成反应;与HX的加成反应均按马可尼可夫规则进行,加成反应活性是HI>HBr>HCl. 文中还研究了双(2-溴丙基环戊二烯基)金属衍生物中C—Br的反应活性,它们与硫氰酸钾、五氯苯酚钠和六次甲基四胺反应得到2-硫氰基、2-五氯苯氧基和2-氨基丙基环戊二烯基金属衍生物。     

低价钛盐还原反应的研究——Ⅲ.2,2-二芳基-1,l,l-三氯乙烷与低价钛盐的反应

2,2-二芳基-1,1,1-三氯乙烷(1)与TiCl_4-Zn起脱氯还原重排反应生成1,2-二芳基乙烯(3)。与TiCl_4-Mg反应时,2,2-二(对甲苯基)-1,1,1-三氯乙烷和2,2-二(对乙氧苯基)-1,1,1-三氯乙烷(1c,1d)主要得到重排产物2,2-二芳基乙烯(3)和2,2-二芳基-1-氯乙烯(4),后者可能是由相应的2,2-二芳基-1,1-二氯乙烷(2)生成的。但2,2-二苯-1,1,1-三氯乙烷和2,2-二(对氯苯基)-1,1,1-三氯乙烷(1a,1b)与此试剂反应只生成还原产物2,2-二芳基-1,1-二氯乙烷(2a,2b)。     

碳铂类似物的合成,表征及对大鼠W—256肉瘤的抑制作用

合成了十八种〔PtA_2X〕·yH_2O,其中A分别为NH_3、CH_3NH_2、1/2乙二胺和1/2(2,3-二甲基-2,3-丁二胺),X分别为1,1-环丙烷二羧酸根(CPrDCA)、2-甲-1,1-环丙烷二羧酸根(2-M-CPrDCA)、2-甲-1,1-环丁烷二羧酸根(2-M-CBDCA)、1,2-环戊烷二羧酸根(CPDCA)和1,1-环已烷二羧酸根(CHDCA),并进行了表征。测定了配合物抑制大鼠W-256肉瘤的活性,发现配合物〔Pt(NH_3)_2X〕系列按X不同有以下的活性次序:CPrDCA>2-M-CPrDCA>CPDCA>CBDCA(碳铂)≥2-M-CBDCA。     

3-羟基-3-甲基-2-丁酮和苯甲酰甲酸甲酯热分解反应的 理论研究

用从头算的方法在6-31G水平上研究了3-羟基-3-甲基-2-丁酮(1)和苯甲酰甲酸甲酯(2)热分解反应的机理。结果是:前一反应是经历五元环过渡态到达氢键中间体,它接着直接分解成乙醛的异构体和丙酮,最后乙醛的异构体异构化成乙醛;后一反应经历六元环过渡态形成中间体1(INT1),中间体1(INT1)直接分解成中间体2(INT2)和甲醛,中间体2(INT2)经过第二个过渡态分解成苯甲醛的异构体和一氧化碳,最后苯甲醛异构体异构化成苯甲醛。其中氢迁过程是反应的速控步骤。在MP~2/6-31G//HF/6-31G+ZPE水平上,对应于这两个反应速控步骤的活化位垒分别是251.42kJ/moL和247.94kJ/mol。采用传统过渡态理论计算了两反应的热反应速率常数,理论的计算结果与实验值吻合较好。     

Addition of hydrogen halides to alkylidenecyclopropanes: a highly efficient and stereoselective method for the preparation of homoallylic halides

The reaction of alkylidenecyclopropanes with HCl or with HBr proceeds very smoothly at 120°C to produce the corresponding homoallylic halides stereoselectively in good to excellent yields. For example, the reaction of (1-phenylbenzylidene)cyclopropane, (1-butylpentylidene)cyclopropane and octylidenecyclopropane with hydrochloric acid produced the corresponding homoallylic chlorides, 4-chloro-1,1-diphenyl-1-butene, 4-butyl-1-chloro-3-octene and (E)-1-chloro-3-undecene in 99, 96, and 87% yields, respectively. The reaction of (1-butylpentylidene)cyclopropane with hydrobromic acid yielded 1-bromo-4-butyl-3-octene in 95% yield.     

Lower photoreactivity of 3-methyl-3-(4′-biphenylyl)-t-butene

Direct and sensitized photolyses of 3-methyl-3-(4′-biphenylyl)-1-butene gave 1,1-dimethyl-2-(4′-biphenylyl)cyclopropane as primary product and 2-methyl-4-(4′-biphenylyl)-1-butene as secondary product with quantum yields of 7.6×10^?3 and 5.6×10^?3, respectively. On direct photolysis, the triplet reactant rearranged with a quantum yield of 4.4×10^?3 and is more reactive than the singlet. The exceptionally low photoreactivity shows that the excitation energy is largely localized on the biphenylyl portion but can be delivered to the reaction center slowly.     

Reactions of unsymmetrically substituted allyl radicals with methyl radicals

The Hg(6³P₁) photosensitized decompositions of 3-methyl-1-butene, 2-methyl-2-butene, 3,3-dimethyl-1-butene, and 2,3-dimethyl-1-butene have been used to generate 1-methylallyl, 1,2-dimethylallyl, 1,1-dimethylallyl, and 1,1,2-trimethylallyl radicals in the gas phase at 24 ± 1°C. From a study of the relative yields of the CH₃ combination products, the relative reactivities of the reaction centers in each of these unsymmetrically substituted ambident radicals have been determined. The more substituted centers are found to be the less reactive, and this is ascribed primarily to greater steric interaction at these centers during reaction. Measurement of the ratio of trans- to cis-2-pentene formed from the 1-methylallyl radical, combined with published values for this ratio at higher temperatures, enabled the differences in entropy and heat of formation of the trans- and cis-forms of this radical to be calculated as 0.62 ± 0.85 J mol^?1 K^?1 and - 0.63 ± 0.25 kJ mol^?1, respectively, at 298K. Approximate values of the disproportionation/combination ratios for reaction of CH₃ with 1,1-dimethylallyl and 1-methylallyl have been estimated and used to compute rate constants for the recombinations of tert-butyl and isopropyl radicals that are in agreement with recently published data.     

Synthesis and some transformations of bicyclic γ-lactones with a fused cyclopropane ring

Reductive cyclization of 4-hydroxymethyl-5,5-dimethyl(or pentamethylene)-2,5-dihydrofuran-2-ones by the action of sodium tetrahydridoborate gave bicyclic compounds in which the lactone ring is fused to a cyclopropane ring. Hydrolysis of the products with aqueous sodium hydroxide resulted in the formation of the corresponding disodium cyclopropane-1,1-dicarboxylates, which reacted with alkyl halides to produce the diesters. Acid hydrolysis of the fused systems was accompanied by opening of the cyclopropane ring with formation of 4-chloromethyl-5,5-dimethyl-2-oxotetrahydrofuran-3-carboxylic acid.     

New efficient approach to 2,2-diaryl-1,1-difluoro-1-alkenes and 1,1-difluoro-2-aryl-1,3-dienes via Suzuki coupling of alpha-halo-beta,beta-difluorostyrenes

[reaction: see text] Alpha-halo-beta,beta-difluorostyrenes [ArCX = CF2; X = Br, I; Ar = aryl, heteroaryl; synthesized by the Pd(0)-catalyzed coupling reaction of the corresponding alpha-halo-beta,beta-difluoroethenylzinc reagents (CF2=CXZnCl, X = Br, I) with aryl iodides] were functionalized at the halogen site with arylboronic acids under Pd(0)-catalyzed Suzuki-Miyaura coupling reaction conditions to obtain 2,2-diaryl-1,1-difluoro-1-alkenes (ArAr'C=CF2, Ar' = aryl, heteroaryl) in 51-91% isolated yield. The corresponding reaction with alkenylboronic acids produced 1,1-difluoro-2-aryl-1,3-dienes in 53-80% isolated yield. Alternatively, 2,2-disubstituted-1,1-difluoro-1-alkenes were synthesized in moderate yield by a zinc-insertion reaction at the halogen site of the alpha-halo-beta,beta-difluorostyrenes, followed by Pd(0)-catalyzed cross-coupling of the zinc reagent with aryl or alkenyl iodides.     

Thermal rearrangement of substituted difluoro(methylene)cyclopropane

Both experimental and computational approaches have been employed in the present work to investigate the thermal conversion of substituted difluoro(methylene)cyclopropanes (F₂MCP) E-1,1-difluoro-2,2-dimethyl-3-tosylmethylene cyclopropane 1, to the thermodynamically more stable F₂MCP products, 1,1-difluoro-2-tosyl-3-(propan-2-ylidene)cyclopropane 2, and 1-(3-(difluoromethylene)-2,2-dimethylcyclopropylsulfonyl)-4-methylbenzene 3. The X-ray crystal structure has been obtained for both 1 and 2, respectively, based on which theoretical analyses on their structure and stability have been carried out. Possible reaction mechanisms are proposed.     

Rate constants for the gas-phase reaction of C5?C10 alkenes with ozone

The gas-phase reaction of ozone with C₅? C₁₀ alkenes(eight 1-alkenes, four 1,1-disubstituted alkenes, and cyclohexene) has been investigated at atmospheric pressure and ambient temperature (285–293 K). Cyclohexane was added to scavenge the hydroxyl radical, which forms as a product of the ozone-alkene reaction. The reaction rate constants, in units of 10^?18 cm³ molecule^?1 s^?1, are 9.6±1.6 for 1-pentene, 9.7±1.4 for 1-hexene, 9.4±0.4 for 1-heptene, 12.5±0.4 for 1-octene, 8.0±1.4 for 1-decene, 3.8±0.6 for 3-methyl-1-pentene, 7.3±0.7 for 4-methyl-1-pentene, 3.9±0.9 for 3,3-dimethyl-1-butene, 13.3±1.4 for 2-methyl-1-butene, 12.5±1.1 for 2-methyl-1-pentene, 10.0±0.3 for 2,3-dimethyl-1-butene, 13.7±0.9 for 2-ethyl-1-butene, and 84.6±1.0 for cyclohexene. Substituent effects on alkene reactivity are examined. Steric effect appear to be important for all 1,1-disubstituted alkenes as well as for those 1-alkenes that bear s-butyl and t-butyl groups. The results are briefly discussed with respect to the atomospheric persistence of the alkenes studied. © 1995 John Wiley & Sons, Inc.     

1,1-Dimethyl-1-(trialkoxysilylmethyl)hydrazinium and 1,1-Dimethyl-1-(silatranylmethyl)hydrazinium Halides

Formerly unknown 1,1-dimethyl-1-(trialkoxysilylmethyl)- and 1,1-dimethyl-1-(silatranylmethyl)hydrazinium halides were prepared by reaction of 1,1-dimethylhydrazine with (halomethyl)trialkoxysilanes XCH₂Si(OR)₃ (X = Cl, I; R=Me, Et) and 1-(halomethyl)silatranes XCH₂Si(OCH₂CH₂)₃N (X = Cl, Br). 1,1-Dimethyl-1-(silatranylmethyl)hydrazinium chloride and iodide were also obtained by transetherification of corresponding 1,1-dimethyl-1-(trimethoxysilylmethyl)hydrazinium halides with tris(2-hydroxyethyl)amine.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 915–919.Original Russian Text Copyright © 2005 by Sorokin, Voronkov.     

Synthesis and reactions of pyrazole-4-carbaldehydes

1-, 3-, and 5-Alkylpyrazoles, as well as linearly bridged bis-pyrazoles, were converted into the corresponding 4-formyl derivatives by Vilsmeier-Haak reaction both under standard conditions and under microwave activation in DMF over a period of 10 min. 1,1′-(Hexane-1,6-diyl)bis(3,5-dimethyl-1H-pyrazole) and 1,1′-(benzene-1,4-diyldimethylene)bis(3,5-dimethyl-1H-pyrazole) gave rise to 4-formyl derivatives at both pyrazole rings. 5-Chloro-1,3-dialkyl-1H-pyrazoles failed to undergo formylation according to Vilsmeier-Haak or under microwave activation. 1,1′-Bridged bis-3,5-dimethyl-1H-pyrazoles reacted with 2-sulfanylethanol on heating in the presence of chloro(trimethyl)silane to give the corresponding bridged bis-4-(1,4,6-oxadithiocan-5-yl)-1H-pyrazoles.     

A comparison of hydrogen bonding solvent effects on the singlet oxygen reactions of allyl and vinyl sulfides, sulfoxides, and sulfones

The singlet oxygen (¹Δ_g) photooxidations of 2-methyl-3-phenylthio-2-butene (1a), 1-[(4-nitrophenyl)thio]-2,3-dimethyl-2-butene (2c), 2-methyl-3-phenylsulfinyl-2-butene (3), 2-methyl-3-phenylsulfonyl-2-butene (6), and 1-[(4-nitrophenyl)sulfonyl]-2,3-dimethyl-2-butene (7c) were conducted in the following deuterated solvents: acetonitrile, benzene, chloroform, methanol, or methanol/water mixture. In each case the ene allylic hydroperoxide products and/or the [2+2] cycloaddition products were quantified and inspected for possible hydrogen bonding induced differences in product selectivity and regiochemistry. After comparison to literature values for related substrates, the results indicate that only photooxidations of vinyl sulfides are susceptible to hydrogen bonding solvent effects.