نتایج جستجو برای: fiedel crafts cyclisation
تعداد نتایج: 2582 فیلتر نتایج به سال:
In this article, the historical use of crafts in occupational therapy for the physically disabled patient is reviewed and the results of a survey aimed at describing current craft use is presented. A questionnaire was sent to a random sample of 250 occupational therapists throughout the United States who chose physical disabilities as their specialty section. Results demonstrated that, while mo...
Lycoposerramine A (1) is a pentacyclic alkaloid isolated in 2001 by Takayama and co-workers. A concise synthesis of a model compound 8 for the tetracyclic core of this natural product is described. Key steps include the desymmetrising free-radical cyclisation of compound 7 to give compound 18 and spirocyclisation of compound 26 to give compound 8. Earlier approaches using a novel high-yielding ...
2-(Pyrrol-1-yl)phenoxyl, aminyl, thiophenoxyl and benzyl radicals 2a-2d, respectively, were generated in the gas-phase under flash vacuum pyrolysis conditions. In all cases except the phenoxyl, cyclisation took place providing acceptable synthetic routes to the fused heterocycles 11, 14 and 15, respectively. Only sigmatropic rearrangement products were isolated, in low yields, from the phenoxyl...
The valuable tetrahydro-?- and ?-carboline skeleta can be accessed through Pictet-Spengler cyclisation initiated by acceptorless dehydrogenation of saturated cyclic amines. substrate scope for the ?-isomers is found to somewhat limited, but access ?-isomers more reactive 2-(aminoethyl)indoles general. synthetic utility hydrogen transfer catalysis highlighted in a two-step preparation alkaloid d...
The development of efficient Friedel-Crafts alkylations of arenes and heteroarenes using only catalytic amounts of a Lewis acid has gained much attention over the last decade. The new catalytic approaches described in this review are favoured over classical Friedel-Crafts conditions as benzyl-, propargyl- and allyl alcohols, or styrenes, can be used instead of toxic benzyl halides. Additionally...
This study mainly concentrates on metallurgical structure of the ferrous ancient crafts, specially the discovered ferrous man-made pieces in Ilam which are aged more than 3000 years. The pieces were discovered in Ize a town located in the south east of Ahvaz , in the southern of Iran. The crafts include an ferrous bar, a 3-side and a 4 side bayonets which were microscopically studied by Electro...
The electrochemical intramolecular cyclisation of bromoalkoxylated derivatives 1 was carried out using Ni(II) complexes as the catalysts in ethanol solutions by constant-current electrolysis in one-compartment cell in the absence of sacrificial anodes as an environmentally friendly system. The reduction of the substrates proceeds via one-electron cleavage of the carbon–bromine bond to form radi...
Cyclisation of d-(N.N-dimethylhydrazono)alkyl phosphites af forded the title compounds in modera te to high yields. The ring closure was highly diastereoselective leading to an excess of the diastereomers with the /3,/3-dimethylhydrazino and M e O P groups in the trans configuration. The structure and relative configurations of diastereomeric pairs were established by ' H and C N M R spectrosco...
Under radical reaction conditions, two different and competitive reaction pathways were observed for N-(α-methylbenzyl)trichloroacetamides with a N-3-cyclohexenyl substituent: 1,4-hydrogen translocation and radical addition to a double bond. However, for radicals with an acyclic alkenyl side chain, the direct cyclisation process was exclusively observed. The dichotomy between translocation and ...
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