共查询到20条相似文献,搜索用时 15 毫秒
1.
The iron-catalyzed 2-arylbenzoxazole formation from o-nitrophenols and benzylic alcohols using hydrogen transfer is described. Various 2-arylbenzoxazoles were selectively obtained in good to excellent yields. The reaction tolerated a wide range of functionalities. The alcohol oxidation, nitro reduction, condensation, and dehydrogenation were realized in a cascade without external reducing reagent and oxidant. 相似文献
2.
3.
Garcia P Evanno Y George P Sevrin M Ricci G Malacria M Aubert C Gandon V 《Organic letters》2011,13(8):2030-2033
Bimolecular cobalt-catalyzed [2 + 2 + 2] cycloadditions between yne-ynamides and nitriles afford bicyclic 3- or 4-aminopyridines in up to 100% yield. The high regioselectivity observed depends on the substitution pattern at the starting ynamide. Aminopyridines bearing TMS and Ts groups are efficiently deprotected in an orthogonal fashion. 相似文献
4.
A general and facile one-pot amination procedure for the synthesis of 2-aminopyridines from the corresponding pyridine-N-oxides is presented as a mild alternative to S(N)Ar chemistry. A variety of amines and heterocyclic-N-oxides participate effectively in this transformation which uses the phosphonium salt, PyBroP, as a means of substrate activation. 相似文献
5.
The iron-catalyzed heterocyclizations from 2-nitroanilines and benzylic alcohols to form benzimidazoles using hydrogen transfer reaction were investigated in this study. In the presence of dppf in toluene at 150 °C, various benzimidazoles were obtained in moderate to good yields within 24 h. The reaction was proposed to proceed via a cascade of alcohol oxidation, nitro reduction, condensation, and dehydrogenation. 相似文献
6.
Metal-carbynes RCM(CO)4Br with diacetylenes give specific phenols in good yield. The reactions take only a few minutes at or below room temperature. 相似文献
7.
The reaction of 2-aminopyridines with PCl5 proceeds with the formation of 2-trichlorophosphazopyridines, which when treated with morpholine are converted to 2-dimorpholidochlorophosphazopyridines. By heating these last products with 96% ethanol, dimorpholido pyridyl-2-amidophosphoric acids are obtained. 相似文献
8.
Iron(III) salts catalyze the tandem rearrangement/hetero-Diels-Alder reaction of 2H-chromenes to yield tetrahydrochromeno heterocycles. The process can occur as a homodimerization and cycloaddition process using electron-rich dienophiles. Deuterium labeling and mechanistic studies revealed a hydride shift and ortho-quinone methide cycloaddition reaction pathway. 相似文献
9.
Xavier Bantreil Nasreddine Kanfar Nicolas GehinEthan Golliard Pauline OhlmannJean Martinez Frédéric Lamaty 《Tetrahedron》2014
A convenient and user-friendly method to yield benzamides from primary and secondary amines and various benzylic alcohols in the presence of a cheap iron salt (FeCl2·4H2O) and tert-butylhydroperoxide (70% in water) as a stoichiometric oxidant is described. Control experiments indicated that this reaction might involve radical species. This method proved to be general, generating a family of 30 benzamides and was applied to the preparative synthesis of anti-anxiety drug moclobemide. 相似文献
10.
Synthesis of functionalized siloles from Si-tethered diynes 总被引:1,自引:0,他引:1
A new synthetic itinerary to silole from Si-tethered diynes is reported. In this protocol, the Si-tethered diyne manifests definitely the reactivity of monoyne to form the lithio silole via zirconacyclopetadiene, 1,4-diiodo-1,3-butadiene, and the corresponding dilithiodiene successively. Lithio siloles thus obtained above could be easily functionalized to give various types of silole derivatives. Complex structure like bridged bis-silole compounds could also be constructed by this process. 相似文献
11.
CpCo(CO)2-mediated cyclotrimerisation of bis-alkynes and cyanamides provides multisubstituted 2-aminopyridines, including macrocyclic products, such as 22 (50% yield). 相似文献
12.
Scheffer U Strick A Ludwig V Peter S Kalden E Göbel MW 《Journal of the American Chemical Society》2005,127(7):2211-2217
2-aminopyridine and 2-aminobenzimidazole were chosen as structural analogues to substitute guanidinium groups in receptor molecules designed as phosphoryl transfer catalysts. Shifting the pKa of the guanidinium analogues toward 7 was expected to raise catalytic activities in aqueous buffer. Although the pKa's of both heterocycles are similar (6.2 and 7.0), only 2-aminobenzimidazole led to active RNA cleavers. All cleavage assays were run with fluorescently labeled substrates and a DNA sequencer. RNase contaminations would degrade RNA enantioselectively. In contrast, achiral catalysts such as 9b and 10b necessarily induce identical cleavage patterns in RNA and its mirror image. This principle allowed us to safely rule out contamination effects in this study. The most active catalysts, tris(2-aminobenzimidazoles) 9b and 10b, were shown by fluorescence correlation spectroscopy (FCS) to aggregate with oligonucleotides. However, at very low concentrations the compounds are still active in the nonaggregated state. Conjugates of 10b with antisense oligonucleotides or RNA binding peptides, therefore, will be promising candidates as site specific artificial ribonucleases. 相似文献
13.
Alkylation of 2-mercaptopyridine with 1,2-dibromoethane affords a cyclic dihydrothiazolopyridinium salt that can serve as a precursor of 2-aminopyridines. Its reaction with primary or secondary amines, either neat or in DMSO, under mild conditions gives the title compounds. 相似文献
14.
15.
The structure (III) reported by Lappin (2) for the diadducts formed by the reaction of methyl propiolate with 2-aminopyridines has been found to be incorrect. The correct structure (IV) has been proven by spectral studies and cyclisation to compound VII. In two cases new compounds having structures of the type (III) have been isolated. N.M.R. data are reported for all products. 相似文献
16.
A safe and facile method for the formation of 3-trifluoromethyl-5-amino-1,2,4-oxadiazoles, via a reversed addition of hydroxylamine to cyanamides, is reported. This two-pot procedure is suitable to scale-up and avoids the hazards associated with trifluoromethyl amidoxime synthesis. 相似文献
17.
Graham R. Lawton 《Tetrahedron letters》2006,47(34):6113-6115
The pyridine nitrogen of the 2-aminopyridine group is sufficiently nucleophilic to undergo intramolecular cyclizations, thereby preventing competing Mitsunobu and other substitution reactions from proceeding at a remote site. Double protection of the 2-amino group effectively blocked reaction at the pyridine nitrogen. This is a rare example of the use of a remote protecting group to block another group from reacting. 相似文献
18.
19.
《Tetrahedron letters》1986,27(39):4783-4786
The allylic rearrangement of cyanamides has been achieved by pyrolysis in solution at temperatures between 125 and 190 °C. This rearrangement was also observed during the thermal opening of the aziridine ring in cyanoaziridines. This allylic transposition constitutes a formal method for the 1,3-isomerization of allylic amines. 相似文献
20.
The cross-coupling of alkyl cyanamides with a number of aryl, heteroaryl, and vinyl halide and pseudohalide coupling partners has been developed via a modification of Pd-catalyzed amidation methods. The reactions proceed selectively under mild conditions with reasonable reaction times in moderate to excellent yields. 相似文献