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1.
Wojciech Dmowski 《Journal of fluorine chemistry》1982,21(2):201-219
1-Phenylpentafluoropropene and its para-substituted analogs are susceptible to nucleophilic attack at both vinylic carbon atoms C-1 and C-2. They react with ethanolio sodium ethoxide to give predominantly substitution products, 1-ethoxy-1-phenyltetrafluoropropenes and 2-ethoxy-1-phenyltetrafluoropropenes , with only little formation of adducts, . 2-ethoxy-1H-1-phenylpentafluoropropanes . Alkenes , where the para-substituent X H,Cl,and CF3 give additionally 1,2-diethoxy-1-phenyltrifluoropropenes and, where X = CF3 also 2,2-diethoxy-1H-1-phenyltetrafluoropropane . Overall regioselectivity of nucleophilic attack of the ethoxide ion on alkenes exhibits the Hammett type correlation with Óp values of substituents X: CH3O and CH3 groups favour the attack on the vinylic carbon C-1, while CF3 and Cl substituents direct the attack on the C-2 carbon of alkenes . The E and Z isomers of 1-ethoxy and 1,2-diethoxy substituted alkenes and were formed in comparable amounts, while the E isomers of 2-ethoxy substituted alkenes were always formed with a 93 – 97 % selectivity. 相似文献
2.
Toshio Hayashi Nobuo Fujitaka Takeshi Oishi Tatsuo Takeshima 《Tetrahedron letters》1980,21(3):303-306
Reactions of the anions of (Z)-2-alkenyl N,N-dimethyldithiocarbamates with benzaldehyde gave the isomers of 4-hydroxy-4-phenyl-(E)-1-alkenyl N,N-dimethyldithiocarbamates stereoselectively and those of the anions of (E)-2-alkenyl N,N-dimethyldithiocarbamates afforded the isomers predominantly. 相似文献
3.
The reaction of Fe(CO)(CH2 CHCHCH2)2 with (Ph2 PCH2)2 results in formation of a mixture of two isomers of Fe(CO)(CH2 CHCHCH2)-(Ph2 PCH2 CH2 PPh2). NMR studies concerning the structures of these isomers and their dynamic behavior in solution are described. 相似文献
4.
Wojciech Dmowski 《Journal of fluorine chemistry》1984,26(3):379-394
1-Phenylpentafluoropropenes readily react with lithium dialkylamides to give, in most cases, mixtures of 1-aminosubstituted alkenes and 2-amino-substituted alkenes , with the latter being the favoured products. The reactions with bulky lithium diethylamide and lithium 2-methylpiperidinoamide gave exclusively 1-amino-substituted products . The effect of the increased bulk of N-nucleophiles is opposite to that observed for the reactions of alkenes with C-nucleophiles Increasing electronegativity of the phenyl ring substituents in alkenes shifts the regioselectivity of the attack of lithium amides towards the C2 carbon atom. The E to Z isomer ratios of enamines were found to be time dependent and the slow isomerisation of the kinetic isomers E to the thermodynamic isomers Z was observed, while the ratio of isomers of enamines did not change with time.A concerted, single-step process is suggested for the reactions of alkenes with lithium dialkylamides, and a tentative explanation of the different stereochemistry of enamines and is given. 相似文献
5.
Ronald L. Bennett Michael I. Bruce F.Gordon A. Stone 《Journal of organometallic chemistry》1975,94(1):65-74
The interaction of azobenzene and MnR(CO)5 (R Me, Et, CH2Ph, CH2-C6Me5, COCF3, COCH2C6F5, COCH2OPh, Ph or C6F5) affords MPh)-(CO)4, together with a binuclear complex Mn2(CO)6(C12H10N2) in some cases. The metallation reaction is shown to proceed most readily with Mn-(CH2Ph)(CO)5; with this reagent, the metallated complexes MMe2)-(CO)3[PMe2(CH2Ph)] (two isomers) and MsMe2(CO)4 have been obtained on treatment with EMe2(CH2Ph) (E P and As, respectively). 相似文献
6.
The CH3O(2E) radical produced by the 266 nm photolysis of CH3ONO is characterized by laser-induced fluorescence. Using a flowing gas cell the reaction rate of CH3O(2E) with NO is measured to be (2.08 ± 0.12) × 10?11 cm3 s?1 molecule?1 based upon disappearance of CH3O and appearance of HNO detected by laser induced fluorescence. Upper limits for CH3O reactions with CH4, CO, N2O, NH3, CH3OH, (CH3)3CH and CH2CHCH2CH3 are reported. These reactions are all too slow to measure under our experimental conditions. 相似文献
7.
Razak J. Al-Essa Richard J. Puddephatt Charles F.H. Tipper Peter J. Thompson 《Journal of organometallic chemistry》1978,157(2):C40-C42
The platinacyclobutane complexes PtCl2L2(C3H5Me)], L pyridine, CD3CN, or tetrahydrofuran, exist as mixtures of isomers containing PH2 or P groups in rapid equilibrium. Decomposition occurs in some cases to give [PtCl2L(CH3CH2CHCH2)]. Stereospecific skeletal isomerisation also occurs in metallocyclobutanes containing the groups PH2 PHR, when R aryl further decomposition gives ν-allylplatinum complexes. 相似文献
8.
The title compound // may be transformed into the 3-/methylaminomethylene/--2,3,6,7,8,9-hexahydro-4H-pyrido[1,2-a]pyrimidine-2,4-dione /E, Z/ which is in equilibrium with the 1,2,3,6,7,8-hexahydro tautomer /E, Z/ in DMSO-d6. 相似文献
9.
(E)- and (Z)-1-benzenesulfonyl-4-trimethylsilyl-2-butenes (E/Z=9), prepared from 4-trimethylsilyl-1-buten-3-ol, -butyllithium and benzenesulfenyl chloride and oxidation of the intermediate (E)- and (Z)-1-benzenesulfinyl-4-trimethylsilyl-2-butenes with hydrogen peroxide, react with -butyllithium and then primary halides to give 4-benzenesulfonyl-1-trimethylsilyl-2-alkenes which are rapidly 1,4-debenzenesulfonyltrimethylsilated to (E)-1,3-alkadienes by tetra--butylammonium fluoride at O°C. 相似文献
10.
α,β-epoxy-artemisia ketone, undergoes intramolecular cyclisation by OM-DM yielding the tetrahydrofuran derivatives – , while on treatment with BF3,-etherate cyclises to the cyclopentanones and . The structure of all products has been elucidated by spectral methods. The mechanism of the cyclisation reaction is discussed briefly. 相似文献
11.
Thermal rearrangement and acid-catalyzed cyclization of all possible geometrical isomers of hedycaryol were investigated. From the stereochemistry of the products, the reacting conformations were deduced. While three (E,E-, E,Z- AND Z,E-) isomers reacted through the crossed conformations, Z,Z-isomer yielded products parallel conformations. The thermal reaction at higher temperatures revealed the additional pathways involving Cope rearrangement of elemols. All possible stereoisomers of elemol were synthesized. The structure of “epielemol” has to be revised. 相似文献
12.
A structure with a pyramidal -CF2 group is shown to desribe satisfactorily hyperfine interactions in CH2CF radical anions within the framework of the INDO method. The factors responsible for the substantial difference in the degree of spin density delocalization on F in CH2CF and C2F are analyzed. 相似文献
13.
Unstable transition metal compounds formed from hydridosilacyclobutanes are described: 1-methyl-1-silacyclobutane reacts with nonacarbonyldiiron to give the complexes [Fe(CO)4(H){H2}] and [(H)Me}(CO)4], and with bis(triphenylphosphine)(ethylene)platinum(0) to give [Pt(H)(PPh3)2{H2}]. 相似文献
14.
Some new β-diketone derivatives of boron having the general formula B2O(OAc)4?n[OC(R) CH3]n (where n = 1 or 2; R = CH3, C2H5, C6H5 and p-ClC6H4) have been synthesised by the reactions of oxy-bis(diacetatoborane) and substituted pyrazolones, such as 4-acyl-3-methyl-1-phenyl-2-pyrazolin-5-ones (acyl = acetyl, propionyl, benzoyl and p-chlorobenzoyl) in dry toluene solution in 1:1 and 1:2 molar ratios. These derivatives have been characterised by elemental analysis, molecular weight measurements. Structures have been proposed on the basis of chemical reactions, IR, 1H and 11B NMR spectral studies.In the derivatives B2O(OAc)3[OC(R) CH3] two of the three acetate groups are unidentate and the third is bridged between two boron atoms along with BOB linkage. Whereas the derivatives B2O(OAc)2[OC(R) CH3]2 are the mixture of geometrical isomers. 相似文献
15.
Comparative study on the proton and carbon NMR spectra for a series of - and -acyl substituted monohydroxypyridines (C5H4NO: =-H, -CHO, -COCH3, -COC(CH3)3, -COCF3, -COC6H5, -SO2CH3, -SO2C6H4CH3 is reported. p]Characteristic 1H, 13 NMR and IR spectral features allow simple and unambiguous distinction between the isomeric - and/or -acyl-derivatives of 2-, 3- and 4-hydroxypyridines, so that both forms can clearly be identified when tautomeric equilibria occur, since the tautomerism rate is slow on the NMR time scale 相似文献
16.
The two C6, C7 substituted title compounds have been synthesized via stereoselective 5--Trig ringclosures starting from (E)-resp. (Z)-4-nonene-1-yl bromide and 3,5-morpholinedione. 相似文献
17.
Oxidation of the complexes -[M(CNR)2(dppe)2] (A) (M = Mo or W; R = Me, But or CH3C6H4-; dppe = Ph2PCH2CH2PPh2) with diiodine or silver (I) salts gives the paramagnetic cations -[M(CNR)2(dppe)2]+, (M = Mo, R = CH3C6H4-; M = W, R = But) and -[M(CNR)2(dppe)2]2+ (M = Mo, R = Me or CH3C6H4-; M = W, R = Me or But). Mixtures of products are generally produced when dichlorine or dibromine are the oxidising agents, however pure salts, the seven-coordinate complex cations [MX(CNC6H4CH3-)2(dppe)2]+ (B, X = Cl or Br) have been isolated. A simple molecular orbital scheme is proposed for complexes (A) and used to discuss their electronic spectra and their oxidation. 相似文献
18.
19.
The preparation, properties and the complexation behaviour of o-lithiobenzyldiorganoarsines are described. Halogen-bridged binuclear complexes of the type [μ-ClR2)]2 (M = Pd, Pt; E = N,P) react with o-LiC6H4CH2ER2 (E = N, P, As), to form asymmetric metallacycles with two different donor atoms in the molecule. Some physical and chemical properties of these interesting complexes are discussed. 相似文献
20.
Iodine-mediated cyclization of (Z)- and (E)-{=D}-ribohept-2-enonates and gave exclusively the β-ribofuranose and α-ribofuranose derivatives and , respectively. Cyclization of the (Z)- and (E)-2-heptene-1-ol derivatives and gave ribofuranose products ( and ) and a ribopyranose (), respectively. 相似文献