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1.
A novel synthesis of 3-substituted-3,4-dihydro-2H-1,3-benzothiazin-2-ones is described herein. The strategy relies on a highly regioselective palladium-catalyzed carbonylation of 2-substituted-2,3-dihydro-1,2-benzisothiazoles to give the corresponding 3,4-dihydro-2H-1,3-benzothiazin-2-one derivatives in good to excellent yields. 相似文献
2.
3,4-Dihydro-2H-1,3-benzoxazines were prepared from primary amines and dihalocompounds by a method which can lead to compounds dissymetrically substituted in positions 2 and 4. 相似文献
3.
Tetrazolo[1,5-a]pyridines/2-azidopyridines 1 undergo photochemical nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes 3, which react with alcohols to afford 2-alkoxy-1H-1,3-diazepines 4 (5), with secondary amines to 2-dialkylamino-5H-1,3-diazepines 16, sometimes via isolable 2-dialkylamino-1H-1,3-diazepines 15, and with water to 1,3-diazepin-2-ones 19. The latter are also obtained by elimination of isobutene or propene from 2-tert-butoxy- or 2-isopropoxy-1H-1,3-diazepines 4 or 5. 1,3-Diazepin-2-one 22B and 1,3-diazepin-4-one 24 were obtained from hydrolysis of the corresponding 4-chlorodiazepines. Diazepinones 19 undergo photochemical ring closure to diazabicycloheptenones 25 in high yields. The 2-alkoxy-1H-1,3-diazepines 4 and 5 interconvert by rapid proton exchange between positions N1 and N3. The free energies of activation for the proton exchange were measured by the Forsén-Hoffman method as DeltaG([double dagger])298= 16.2 +/- 0.6 kcal mol(-1) as an average for 4a-c in CD2Cl2, acetone-d6, and methanol-d4, and 14.1 +/- 0.6 kcal mol(-1) for in 4c acetone/D2O. The structures of 2-methoxy-5,6-bis(trifluoromethyl)-1H-1,3-diazepine 4k, 1,2-dihydro-4-diethylamino-5H-1,3-diazepin-2-one 22bB, and diazabicycloheptanone were 26 determined by X-ray crystallography. The former represents the first reported X-ray crystal structure of any monocyclic N-unsubstituted 1H-azepine. 相似文献
4.
We report the synthesis of several substituted 3,4-dihydro-2H-1,3-benzoxazines by simple ring closure of 2-hydroxybenzylamines with paraformaldehyde. The facile synthesis of the benzylamine precursors from commercially available salicylaldehyde derivatives affords a powerful general synthetic way to prepare a variety of substituted benzoxazines, avoiding the formation of undesirable oligomeric species, thus leading to a simple workup and improving the yield and purity of the final product. This straightforward method allows synthesis of hydroxy-substituted and deuterium-labeled 1,3-benzoxazines that are not attainable using other synthetic ways. 相似文献
5.
6.
Treatment of tetrahydro-2H-1,3-oxazin-2-one (1) or the 3-methyl derivative 2 with aniline salts or thiophenols at 180 °C affords the corresponding N-aryl-1,3-propanediamines 3 or 3-(arylthio)propanamines 4 in good yields. 相似文献
7.
3,4-Dihydro-2H-1,3,5-thiadiazines substituted at the 3 and 6 positions were synthesized by treatment of N-substituted N,N-bis(1H-1,2,3-benzotriazol-1-ylmethyl)-amines with thioamides and zinc bromide in dry CH(2)Cl(2) at room temperature for 48-60 h in 48-80% yields. 相似文献
8.
To study the synthesis of 3,4-dihydro-2H-3-phenyl-1,3-benzoxazine (benzoxazine), the reaction paths of phenol, aniline and formaldehyde were investigated by analyzing the synthesis crude products. With the aid of high-performance liquid chromatography (HPLC), chromatographic column and preparative HPLC, seven compounds originated from the crude products were obtained and their chemical structures were elucidated. Possible reaction paths are proposed based on these compounds. Results show that Nhydroxymethyl aniline (HMA) derived from the reaction of formaldehyde and aniline is probably the key intermediate during the reaction. HMA can react with itself or other reactants to form other intermediates, such as 1,3,5-triphenyl-1,3,5-triazinane and 2-((phenylamino)methyl)phenol, and further form benzoxazine and byproducts. 相似文献
9.
Minghao LiYanlong Gu 《Tetrahedron》2011,67(43):8314-8320
An electrophilic ring-opening reaction of 2-aryl-3,4-dihydropyran with many nucleophiles, such as thiophenols, thiols, benzenesulfinic acid, resorcin, 2-methylfuran, benzamide and allyltrimethylsilane, was developed. In the presence of an appropriate catalyst, a product that contains not only a moiety of the nucleophile but also a fragment of 1,3-dicarbonyl compound was obtained. 相似文献
10.
Photochemical behaviour of 3,4-epoxy-3,4-dihydro-2H-1-benzopyrans, intermediates in the synthesis of pterocarpans, has been
studied in various solvents. While ring contraction leading to 2,3-dihydrobenzofurans through a photodecarbonylation process
was observed in cyclohexane, photoisomerisation leading to 3-chromanones was observed in acetone. This study has also been
extended to antijuvenile hormone precocene(I) oxide. 相似文献
11.
A method for the synthesis of derivatives of previously unknown heterocyclic systems - 3,4-dihydro-2H-[1,3]thiazino[6,5-b]quinolines - has been developed based on 7,8-dimethyl-2-chloro-3-quinolinecarboxaldehyde via the consecutive steps of conversion into its Schiff's base with a primary amine, reduction to the corresponding aminomethyl derivative, conversion to the thiourea with isothiocyanates, and heterocyclization by intramolecular substitution of the chlorine atom. 相似文献
12.
2-Methylthio-4H-1,3-thiazines or their mixtures with 5-alkylidene-4H-5,6-dihydro-1,3-thiazines were obtained by cyclization of methyl N-3-oxoalkyldithiocarbamates in sulfuric acid. The regiospecificity of the reaction is determined by the structures of the starting compounds. The structures of the synthesized thiazines were confirmed by spectral methods of analysis (IR and 1H and 13C spectroscopy).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 991–993, July, 1992. 相似文献
13.
P. L. Ovechkin L. A. Ignatova A. E. Gekhman B. V. Unkovskii 《Chemistry of Heterocyclic Compounds》1974,10(3):310-312
N-Aryl-N′-(2-methyl-4-hydroxy-2-pentyl)thioureas are cyclized in acidic media to 4,4,6-trimethyl-2-arylimino-5,6-dihydro-4H-1,3-thiazines, the methylation of which with methyl iodide gives 4,4,6-trimethyl-2-methylarylamino-5,6-dihydro-4H-1,3-thiazines. 3,4,4,6-Tetramethyl-2-aryliminotetrahydro-1,3-thiazines were synthesized by cyclization of Naryl-N′-methyl-N′-(2-methyl-4-hydroxy-2-pentyl)thioureas. 相似文献
14.
P. L. Ovechkin L. A. Ignatova B. V. Unkovskii 《Chemistry of Heterocyclic Compounds》1972,8(7):856-858
The synthesis of 3,4,4,6-tetramethyl-2-arylimino-2,3-dihydro-4H-1,3-thiazines, which have a fixed imino structure, was accomplished by two methods: by intramolecular rearrangement of 1,4,6,6-tetramethyl-3-aryl-1,2,3,6-tetrahydropyrimidine-2-thiones and by amination of 3,4,4,6-tetramethyl-2,3-dihydro-4H-1,3-thiazine-2-thione methiodide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 941–943, July, 1972. 相似文献
15.
Klaus Burger Ralph Ottlinger 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):47-48
Abstract 2H-1,3-Thiazetes have been supposed to be the intermediates of the photoaddition of thiocarbonyl compounds to nitriles, yielding N-(alkylidene)thiocarboxamides1é. Using the stabilizing effect of trifluoromethyl groups on small ring systems2 we succeeded in synthesizing 2H-1,3-thiazetes as stable compounds3. At elevated temperatures a thermal mobile valence tautomeric equilibrium with N-(perfluoroisopropylidene)thiocarboxamides was observed, which competes with a [2+2] cycloreversion process. 相似文献
16.
G. N. Dorofeenko V. V. Mezheritskii Yu. I. Ryabukhin O. V. Ivanova L. G. Minyaeva 《Chemistry of Heterocyclic Compounds》1977,13(3):253-259
A method was developed for the synthesis of 4-oxo-(-ethoxyvinyl)-4H-1,3-benzoxazinium salts by condensation of oxo-2-alkylbenzoxazinium salts by condensation of oxo-2-alkylbenzoxazinium salts with ethyl orthoformate. During hydrolysis and aminolysis, attack of the nucleophile is directed to the -carbon atom of the benzoxazinium salts. The previously unknown 2-formylmethylene-4-oxo-3,4-dihydro-2H-1,3-benzoxazines and their nitrogen derivatives were obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 322–327, March, 1977. 相似文献
17.
Kruithof A Ploeger ML Janssen E Helliwell M de Kanter FJ Ruijter E Orru RV 《Molecules (Basel, Switzerland)》2012,17(2):1675-1685
Non-fused 3,6-dihydro-2H-1,3-thiazine-2-thiones constitute a so far rather unexplored class of compounds, with the latest report dating back more than two decades. Thiazine-2-thiones contain an endocyclic dithiocarbamate group, which is often found in pesticides, in substrates for radical chemistry and in synthetic intermediates towards thioureas and amidines. We now report the multicomponent reaction (MCR) of in situ-generated 1-azadienes with carbon disulfide. With this reaction, a one-step protocol towards the potentially interesting 3,6-dihydro-2H-1,3-thiazine-2-thiones was established and a small library was synthesized. 相似文献
18.
L. A. Ignatova A. E. Gekhman M. A. Spektor P. L. Ovechkin B. V. Unkovskil 《Chemistry of Heterocyclic Compounds》1974,10(6):662-665
4,4,6-Trimethyl-2-methylarylamino-4H-1,3-oxazines were synthesized by intramolecular cyclization of N-oxoalkyl-S-methylisothioureas.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 764–767, June, 1974. 相似文献
19.
A. L. Mikhal'chuk O. V. Gulyakevich Yu. V. Shklyaev V. S. Shklyaev A. A. Akhrem 《Chemistry of Heterocyclic Compounds》1998,34(5):602-610
Reactions of alkyl-substituted 3,4-dihydroisoquinolines, with 2-acetylcyclopentane-1,3-dione were used to prepare 3,4-dihydroisoquinolinium 2-acetylcyclopentane-1, 3-dionates, which could not be converted into ABCD-tetracyclic derivatives of the 8-azagonane series (benzo[a]cyclopentano[f]quinolizines). The salts obtained were studied and characterized by physicochemical methods. It was shown by combining the NMR and H/D-isotope exchange methods that for 1-alkyl-3,4-dihydroisoquinolines and their salts in solutions, an imine-enamine (iminium-enaminium), and for the 2-acetylcyclopentane-1,3-dione anion, a keto-enol tautomeric equilibrium takes place.Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus', Minsk 220141. Chemical Engineering Institute, Russian Academy of Sciences, Perm'614000. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 681–690, May, 1998. 相似文献
20.
A new nucleophilic 1,3-rearrangement is observed when treating 2-methoxyquinolino-3-lithium with an α-C substituted deoxybenzoin,and this rearrangement yielded an unusual 3,4-disubstituted 3,4-dihydroquinoline.Several similar reactions were designed and executed to investigate this novel 1,3-rearrangement,and a mechanism involving a nucleophilic addition and a following 1,3-rearrangement with an unusual dearomatization on the quinoline ring is proposed. 相似文献