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1.
The conditions for the preparation and cyclisation of the title compounds are described. The stability of the intermediate lithio-thiacyclohexenes is shown to depend on the reaction conditions and the substituents R1-R4. The final products , and arise from via a [1.4] sigmatropic rearrangement, a [1.3]prototropic shift followed by a [2.3] sigmatropic rearrangement, or the elimination of lithium methanethiolate respectively. 相似文献
2.
2,4,6-Triphenylpyrylium with thiosemicarbazide and thiocarbohydrazide, gives 2-pyrazolines and which undergo cyclization yielding pyrazolo(1,5-c]pyrimidine 5 and pyrazolo [2,3-d]-1,2,4-triazepine derivatives, respectively. Reaction of with phenacyl bromides gave 1,3-thiazolo[3,2-b]pyrazolo [2,3-d]-1,2,4-triazepin-4-iums . Compound on treatment with phenacyl bromides gave 1-(4'-aryl-thiazol-2'-yl)-2-pyrazoline derivatives . Compound reacts with acyl chlorides to give pyrazolo[1,5-c]pyrimidine derivatives , and with aromatic aldehydes giving the 2-(Δ2'1 pyrazolin-1-yl)-5-aryl-1,3,4-Δ2-thiadiazolines which were easily converted to the corresponding 2-(Δ2-pyrazolin-1-yl)-5-aryl-1,3,4-thiadiazoles . 相似文献
3.
The diborane-mediated reduction of labile β-diketones 4, 5 and 6 has been employed as the key step in the synthesis of the three polyquinanes, all--tetracyclo-[6.6.0.01,5.08,12]tetradecane 1, all--tricyclo[6.3.0.01,5]undecane 2 and all--tetracyclo-[5.5.1.04,13.O10,13]tridecane, staurane 3, respectively. 相似文献
4.
The synthesis of tetracyclo[5.4.1.04,12.09.12]dodecan-6-one via an intramolelecular photocycloaddition, its reduction to the hydrocarbon and its ring-contraction to tetracyclo-[4.4.1.03,11.09,11]undecane derivative is described. 相似文献
5.
The mass spectra of metastable molecular and fragment ions demonstrate that the loss of CH3. from [1-methylcyclobutanol].+ leads competitively to three different ions: = protonated cyclobutanone; = [n-C3H7CO]+ and = protonated methylvinylketone. 相似文献
6.
Linda A. Motyka 《Tetrahedron letters》1985,26(24):2827-2830
Direct photolysis of 5-chloro-1,4-dihydro-9-methyl-naphthalen-1,4-imine in cyclohexane gave a mixture of 1-chloronaphthalene and isomeric dihydrocyclobut[b]indoles and . Dihydrocyclobut[b]indoles and thermally rearranged to give 1-benzazepines and , respectively. 相似文献
7.
A.A.Leslie Gunatilaka Subramaniam Sotheeswaran H.T.Badra Sriyani Eric S. Waight 《Tetrahedron letters》1982,23(29):2987-2990
Hermonionic acid and its decarboxylated product have been isolated from . 13C NMR spectral and chemical evidence indicate that hermonionic acid is 2-0-[2-(3-methylbut-2-enyl)-3-methoxy- 4-hydroxy-5-(3,7-dimethylocta-2,6-dienyl]-4-methoxy-5-(3-methylbut-2-enyl-6-hydroxybenzoic acid. The previously assigned dienone structure for this acid is incorrect. 相似文献
8.
1,2,3,4,7,7-Hexafluorobicyclo[2,2,1]hepta-2,5-diene gave 1,2,3,4-tetrafluorebenzene in at least 73% yield when heated to 450°C in a sealed tube; the CF2 bridge appeared, in part, as octafluorocyclobutane. Nucleophilic attack by sodium methoxide- methanol on the diene occurred exclusively at the CFCF bond, causing the formation of 1,2,4,7,7-pentafluoro-3-methoxybicyclo- [2,2,1]hepta-2,5-diene and a 1,4,5,6,7,7-hexafluoro-5-methoxybicyclo [2,2,1]hept-2-ene thought, on the basis of 19F nmr data, to be the 6--F,5--MeO isomer. Radical attack on 1,2,3,- 4,7,7-hexafluorobicyclo[2,2,1]hepta-2,5-diene by bistrifluoromethyl nitroxide took place at both olefinic sites, with a . 10:1 preference for the CFCF linkage; all three geometrical isomers of 5,6-bis(bistrifluoromethylamino-oxy)-1,4,5,6,7,7- hexafluorobicyclo[2,2,1]hept-2-ene were formed. 相似文献
9.
Maria Luisa Gelmi Donato Pccar Pasqualina Trimarco Mariella Valsecchi Riccakdo Destro Marzia Ballabio 《Tetrahedron》1984,40(20):4025-4032
1R*, 4R*, 5S*, 5'S*-5'-Amino-1'-(4-nitrophenyl)-4',5'-dihydrospiro[bicyclo [2.2. 1]hept-2-ene[5.4]-1',2',3'-triazoles] have been obtained both by ?4 +2]-cycloaddition of cyclopentadiene to amino-methylene-1-(4-nitrophenyl)-4,5-dihydro-v-triazoles and by [3+2]-cycloaddition of 4-nitrophenylazide to 5-aminomethylene-2-norborenes . The configuration has been fully established by X-ray crystallographic analysis. The course of the cycloaddition and the thermal behaviour of are discussed. 相似文献
10.
The photolysis of phenyl alkyl ketones adsorbed on a number of commonly available zeolites (molecular sieves) can result in dramatic changes in Type I/Type II photochemistry.The photochemistry of ketones in ordered environments is a topic of current interest2–4. Environmental effects can have important influence on the conformational flexibility of organic molecules, which in turn can affect the outcome of photochemical reactions5. Two recent reports2,3 on the Norrish Type II reaction in ordered media prompts us to report our initial studies of the photochemistry of a number of phenyl alkyl ketones adsorbed in zeolites.Zeolites are crystalline aluminosilicates of usually well-defined structure6. Within the zeolite framework are a system channels and cavities of varying dimensions(2 – 13Å)6, some of which are capable of adsorption of large organic molecules (e.g., substituted benzenes). Thus the possibility that the internal spaces (or void volumes) of zeolites can exert topological control on organic photochemical reactions warrants investigation, since it is well-known that zeolites display shape-selective catalytic and adsorptive properties in important industrial chemical processes10. However, only a handful of reports of photochemical reactions on zeolites are known4,7–9; the majority of these concern the catalytic splitting of water9. In this study, several commonly available zeolites were studied, and the results are compared to those obtained in homogeneous solution.Phenyl alkyl ketones - were employed in this study. The photochemistry of valerophenone , octanophenone , and α,α-dimethylvalerophenone is relatively well-understood in solution11–13. For and , the photobehaviour is characterized by Type II reaction, to give a triplet 1,4-biradical, which can either fragment, to give acetophenone, or cyclize, to give and cyclobutanols (eqn.1). Type I reaction in not observed. In solution, the ratio of fragmentation of cyclization (F/C) products is ~ 4 for and . In general, the isomer dominates, with t/c = 3 – 5 in benzene, and decreasing to a limit of 1 in more polar solvents (MeOH or micelles)11-–13. For . Type I reaction is observed in addition to Type II. The ratio of Type I/Type II product has been reported to be 0.3 in benzene without added thiol, and 0.6 with added thiol11.Ketones and were deposited on Zeolites Na+-A, Na+-X, Na+-Y, Na+-Mordenite and resembling is also possible, from which cyclization is prohibited. For , Type I reaction is known to compete with the Type II process11. Adsorption of this ketone on Silicalite results in reaction via the least-motion pathway, namely Type I reaction, to give benzaldehyde as the aromatic product. Thus the behaviour of this ketone on Silicalite is quite consistent with the explanation offered for and .Na+-Y is a large pore zeolite, with a pore diameter of ~8 Å and an internal cavity (supercage) of ~13 Å6. Additionally, we have found from related studies16 that of the zeolites capable of adsorbing benzene-type molecules studied in this work, Na+-Y allows the greatest degree of molecular mobility for photogenerated benzyl radical. Thus the observed F/C ratios of less than unity for this zeolite probably reflects the increased mobility of the photogenerated 1,4-biradical, allowing it to undergo ring closure readily. Interestingly, this zeolite also gave an t/c ratio for cyclobutanols of .The results for the other zeolites are not readily distinguishable from those observed in solution, although two of these (Na+-X and Na+-Mordenite) are capable of adsorbing - 6. In any event, these two zeolites offer a medium for Type I/Type II reaction which essentially duplicate the behaviour in solution without the presence of solvent. Additional studies are in progress to further study the use of zeolites as a medium for photochemical reactions. 相似文献
11.
In the presence of titanium tetrachloride, 1,3-bis(trimethylsiloxy)-1-methoxybuta-1,3-diene condenses with hexane-2,5-dione or 2,5-dimethoxytetrahydrofuran to give the 8-oxabicyclo[3.2.1]octyl compounds and respectively, and with 2,6-dimethoxytetrahydropyran to give the 9-oxabicyclo [3.3.1]nonyl derivative . Compound is converted to a compound () which is the 8-oxa analog of cocaine. 相似文献
12.
3-Methylisoxazolo[4,5-c]pyridine on reduction with BH3:THF gave, via the isolable complex , the tetrahydroisoxazolopyridine . The presence of two chlorine atoms at the 4 and 6 positions directed borane attact to the isoxazole ring, yielding the aminoethylpyridine . Both types of reduction were obtained with 6-chloroisoxazolo[4,5-c]pyridine . 相似文献
13.
C. Glidewell G.S. Harris H.D. Holden D.C. Liles J.S. McKechnie 《Journal of fluorine chemistry》1981,18(2):143-154
Fluorination of triphenylarsine oxide by aqueous hydrogen fluoride (1–40%) in the absence of glass readily gives triphenylarsine difluoride. When the reaction with dilute (1%) aqueous hydrogen fluoride is carried out in borosilicate glass apparatus, the glass participates in the reaction resulting in the formation of the crystalline 2:1 adduct 2Ph3AsO·HBF4. Crystals of this compound are monoclinic, 21/, = 12.926(4), = 17.819(6), = 14.994(4) Å, β = 98.97(3)°, Z = 4. The structure contains cations [(Ph3AsO)2H]+ in which O is 2.44(2)Å, and anions BF4?. 相似文献
14.
The geometries and the 1H chemical shifts of dihydropyrene and its benzannelated derivatives – have been studied by means of semiempirical quantum chemical procedures. The calculated bond lengths of and proton shifts of – are in good accord with the corresponding experimental values. We show that monobenzannelation in – causes considerable bond length alternation in the [14] perimeter and hence reduced diatropocity. The same is true for the phenanth-fused dibenzannelated compounds and . On the other hand we report evidence that anth-fused dibenzannelated dihydropyrenes , , and should be characterized by symmetric geometrical structures without significant bond length alternation thus leading to enhanced diatropicity. 相似文献
15.
On acetone-sensitization, 5-bromo-1,3-dimethyluracil ( reacts with Nb-methoxycarbonyltryptamine ( under the assistance of an electron carrier such as 2-methoxynaphthalene to give a coupling product . A mechanism involving a double electron transfer via the triplet state of is proposed. 相似文献
16.
-Phenyl areneselenosulfonates add readily to allenes in a highly regiospecific fashion (eq 3) to give . Oxidation of the PhSe group in to PhSe(O) is followed by [2,3]-sigmatropic rearrangement to and hydrolysis of to the β-arylsulfonyl-substituted allylic alcohol , thereby providing a simple, high-yield route to these interesting compounds. 相似文献
17.
The 1H and 13C nmr spectra of , -9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d6 or alkaline D2O, clearly show that it exists in a --conformation with carboxyl groups, thus being the first case of - preference of a bicyclo[3.3.1] nonan-9-one due to the presence of ,-2,4- substituents. 相似文献
18.
H.I.X. Mager 《Tetrahedron letters》1979,20(37):3549-3552
The pyrazine ring opening is proven by rearrangements leading to benzimidazoles , and . A 4a- to 10a-adduct isomerization ( → ) and the intermediacy of a carbonyl oxide are indicated by pyrimidine ring contractions into and , respectively. 相似文献
19.
Titanium - catalyzed dimerization of cycloheptatriene affords pentacyclo[7.5.0.02,8.05,14.07,11]tetradeca-3,12-diene, , and pentacyclo[8.4.0.03,7.04,14.06,11]tetradeca-8,12-diene, . By heating, is converted quantitatively into . 相似文献
20.
Tsutomu Kumagai Kazuya Murakami Hajime Hotta Toshio Mukai 《Tetrahedron letters》1982,23(45):4705-4708
Upon irradiation, 5-dicyanomethylenebicyclo[2.2.2]octene () gives a highly strained compound, 2,2-dicyanotricyclo[4.2.1.01,3]nonene () in good yield. Of additional interest is the observation that the starting material can be quantitatively regenerated from the photo-product with release of 28.8 kcal/mol. 相似文献