共查询到20条相似文献,搜索用时 46 毫秒
1.
Herbert Muffler Guenter Siegemund Werner Schwertfeger 《Journal of fluorine chemistry》1982,21(2):107-132
4.5-Perfluoro-1.3-dioxolanes are available by reaction of 2(α-chloroalkoxy)perfluoro-carbonyl halides or -ketone with fluoride ions. A mechanism for the intramolecular ring- closure-reaction is proposed. Hydrogen atoms at C-2 in can be exchanged photochemically by chlorine. Starting from the 2-monochloro-derivatives the 2-monofluoro-4.5-perfluoro- 1.3-dioxolanes are formed by reaction with triethylamine- hydrofluoride. 相似文献
2.
New synthesis of Eucarvone , (±)-Nuciferal and (±)-Manicone are described from trimethylsilyl enol ethers , and via their chloromethylenation products by means of a two carbons homologation reaction. 相似文献
3.
Starting from the aldehydes and the acetylene is prepared via the borane by means of a combined Wittig reaction-hydroboration reaction sequence. may be converted into the (E)-6,(Z)-11-hexadecadienylacetate () and the corresponding aldehyde . The synthetic route proceeds with high stereospecifity (isomeric purity of and ? 97%). 相似文献
4.
Hiroshi Onoue Masayuki Narisada Shoichiro Uyeo Hiromu Matsumura Kyo Okada Toshisada Yano Wataru Nagata 《Tetrahedron letters》1979,20(40):3867-3870
Allylazetidinones , , prepared by coupling of allylcoppers with chloroazetidinones , , were converted into carbapenem esters , – using an Emmons-Horner reaction to introduce the 6-side chain and an intramolecular Wittig reaction to form the carbapenem ring system. 相似文献
5.
A new C3-unit substitution reaction at C-4 position of 4- acetoxyazetidinone derivative ( and ) by tetraallyltin () in the presence of 1/10 eq. of BF3-ether in methylene chloride is described. From 4-allylazetidinone derivative () via ylid intermediate () dethiathienamycin () was synthesized. 相似文献
6.
The acid catalysed reaction of 4-oxa-homoadamantan-5-one () with benzene yielded a mixture of 4a-phenyladamantan-2-one (), the equatorial isomer' () and 2-phenyl-2,4-o- benzenoadamantane () A plausible reaction pathway for the occurrence of . is put forward. The structure of , was deduced from spectroscopic data and reaction of the proposed intermediate 2,4a-diphenyladamantan-2-ol () with acid. 2,4-o-Ben-zenoadamantane () is prepared likewise. 相似文献
7.
α-Diazo phosphonates with a conjugated 1,3-diene unit are synthesised by the Bamford-Stevens reaction ( →→). They undergo [4+2]-cycloadditions with the dienophile to form the tetrahydrotriazolopyridazines , which possess an unchanged diazo group. In contrast, dimethyl acetylenedicarboxylate () reacts exclusively with the diazo dipole of to yield the 3H-pyrazoles , which rearrange to by sigmatropic PO-shifts and hydrolyse to form . The diazo compound isomerises to the pyrazole when heated in benzene. 相似文献
8.
Marko Zupan 《Journal of fluorine chemistry》1977,9(3):177-185
Bromofluorination of 1-phenylcyclohexene with N-bromosuccinimide-hydrogen fluoride-pyridine in ether proceeds with Markovnikov-type regioselectivity. The reaction is stereospecific anti. Bromofluorination of 2-phenyl-3-bromocyclohexene results in the formation of -1-bromo, -2-fluoro-2-phenyl, -3-bromocyclohexane. 相似文献
9.
The reaction of both - and -2-amino-1-(1-phenylvinyl)- cyclopentanols with aldehydes affords -2-alkyl--3a-aryl-4-oxo-octahydro indoles stereoselectively. 相似文献
10.
Josefina Garcia Robert Greenhouse Joseph M Muchowski Jose Antonio Ruiz 《Tetrahedron letters》1985,26(15):1827-1830
2-Alkyl-3-cyanoindoles are obtained when 1-alkylmethyl-2-chloro-(or 2-phenylsulfonyl)-3-phenylsulfonylindoles are reacted with excess azide ion (90°/DMF). The reaction is considered to occur by a fragmentation recombination process in which the Schiff's base is of central importance. This proposal is supported by the formation of 2-substituted indole-3-carboxylates from aldehydes and the α-phenylsulfonyl--aminophenylacetic acid ester derivative . 相似文献
11.
The formation of oxetanones from bromoketonee requires the presence of a β-methyl group at C-4. The yield of the reaction → is improved by addition of water to the medium. 相似文献
12.
Three new electron donors, acenaphtho[5,6-]-1,2-dithiole (), acenaphtho[5,6-]-1,2-diselenole (), and acenaphtho[5,6-]-1,2-ditellurole (), can be prepared in 28%, 22%, and 14% yields respectively by reaction of the elemental chalcogens (S, Se, Te) with 5,6-dilithioacenaphthylene (). Compound is generated by treatment of 5,6-dibromoacenaphthylen (), for which a convenient preparation is described, with -butyllithium (2 equiv.) in THF at ?78°C. 相似文献
13.
Tarniko Takahashi Shun-ichi Hirokami Masanori Nagata Takao Yamazaki 《Tetrahedron letters》1985,26(27):3247-3250
Both the irradiation of 4-pyrimidinones () and the reaction of the isolated Dewar 4-pyrimidinones () in aqueous solution gave the corresponding photohydrates () which reverted spontaneously to the starting in the dark reaction. The photohydrates were isolated in crystalline form and their physical properties were determined. 相似文献
14.
The reaction of tigogenin () with amalgamated zinc yields tetrahydrotigogenin () and the furostan . While undergoes acid catalyzed elimination to give the rearranged product , spontaneously decomposes to a mixture of and . 相似文献
15.
A synthesis of dihydropyrones is described involving the dimerisation of tetraketones and thermal reaction of intermediate dienone derived from a dienolic system. 相似文献
16.
17.
The steric and electronic influences of substituents attached to the 1,2-dicarbonyl system on the success of the reaction of 1,2- diketones with dimethyl 3-ketoglutarate have been examined. It is clear from the reaction of with benzil, thienil, furil, and phenanthrenequinone , respectively, coupled with 13C NMR spectroscopy of the reaction intermediates, that steric effects play a major role in the overall success of the reaction to provide . This is analogous to the situation observed earlier with 1,2-diketones, R-CO-CO-R, where R represented an aliptiatic or alicyclic group. 相似文献
18.
Indole was converted into several 2-substituted derivatives by using carbon dioxide both for -protection and to give an intermediate carbanion stabilizing group. -Butyllithium was used as a lithiating agent at the -carbon atom of the indole enamino group. The resulting 2-substituted indole-1-carboxylic acids underwent smooth thermal decarboxylation under mild conditions. Alternatively, with longer reaction times the protecting group is lost during the reaction. 相似文献
19.
A methoxy group on a styrene double bond directs O2 attack , giving 1,4 addition if the phenyl is , or ene reaction if a CH3 is . If no substituent is , 1,4 attack on the phenyl occurs at a slower rate. 相似文献
20.
Alfred Hassner Rosario DCosta Andrew T. McPhail William Butler 《Tetrahedron letters》1981,22(38):3691-3694
Vinylaziridine undergoes reaction with electrophilic acetylenes and olefins to produce 7-membered azepine derivatives. With β-nitro-styrene however, a novel rearrangement occurs, presumably via an ene reaction to form , the structure of which is definitively shown by x-ray diffraction. 相似文献