A direct oxidative approach to alkenyl aldehydes from allyl arenes via allyl sp3 C-H functionalization was disclosed. An inexpensive iron catalyst was employed to facilitate this transformation. The mechanistic studies indicate that the cleavage of the allyl sp3 C-H bond is involved in the rate-determining step. 相似文献
A new method for the preparation of 2-substituted oxazolines by rhodium-catalyzed coupling of alkenes with 4,4-dimethyl-2-oxazoline is reported. The oxazoline products are obtained in good yield with excellent selectivity for the linear product. A variety of alkene substitution patterns and functional groups are tolerated. This procedure represents an attractive alternative to hydroesterification because it does not involve the manipulation of CO gas. 相似文献
Pd-catalysed direct oxidative carbonylation of allylic C-H bonds with carbon monoxide was first described. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalysed allylic carbonylation can be lifted, which provides a new route for accessing more synthetically useful β-enoic acid esters with high regioselectivity. 相似文献
This article describes the copper-catalyzed oxidative trifluoromethylation of heteroarenes and highly electron-deficient arenes with CF(3)SiMe(3) through direct C-H activation. In the presence of catalyst Cu(OAc)(2), ligand 1,10-phenanthroline and cobases tert-BuONa/NaOAc, oxidative trifluoromethylation of 1,3,4-oxadiazoles with CF(3)SiMe(3) proceeded smoothly using either air or di-tert-butyl peroxide as an oxidant to give the corresponding trifluoromethylated 1,3,4-oxadiazoles in high yields. Di-tert-butyl peroxide was chosen as the suitable oxidant for oxidative trifluoromethylation of 1,3-azoles and perfluoroarenes. Cu(OH)(2) and Ag(2)CO(3) were the best catalyst and oxidant for direct oxidative trifluoromethyaltion of indoles. The optimum reaction conditions enable oxidative trifluoromethylation of a range of heteroarenes that bear numerous functional groups. The prepared trifluoromethylated heteroarenes are of importance in the areas of pharmaceuticals and agrochemicals. The preliminary mechanistic studies of these oxidative trifluoromethylations are also reported. 相似文献
In the presence of an easily prepared supported ruthenium hydroxide catalyst, Ru(OH)(x)/Al(2)O(3), various kinds of structurally diverse primary azides including benzylic, allylic, and aliphatic ones could be converted into the corresponding nitriles in moderate to high yields (13 examples, 65-94% yields). The gram-scale (1 g) transformation of benzyl azide efficiently proceeded to give benzonitrile (0.7 g, 90% yield) without any decrease in the performance in comparison with the small-scale (0.5 mmol) transformation. The catalysis was truly heterogeneous, and the retrieved catalyst could be reused for the transformation of benzyl azide without an appreciable loss of its high performance. The present transformation of primary azides to nitriles likely proceeds via sequential reactions of imide formation, followed by dehydrogenation (β-elimination) to produce the corresponding nitriles. The Ru(OH)(x)/Al(2)O(3) catalyst could be further employed for synthesis of amides in water through the transformation of primary azides (benzylic and aliphatic ones) to nitriles, followed by sequent hydration of the nitriles formed. Additionally, direct one-pot synthesis from alkyl halides and TBAN(3) (TBA = tetra-n-butylammonium) could be realized with Ru(OH)(x)/Al(2)O(3), giving the corresponding nitriles in moderate to high yields (10 examples, 64-84% yields). 相似文献
The reaction of various aromatic nitriles with 1.1 equiv of Ti(Oi-Pr)(4) and 2.2 equiv of EtMgBr followed by addition of a Lewis acid gave 1-aryl cyclopropylamines in 43-76% yields. Under similar conditions, conjugated alkenenitriles afford 1-alkenylcyclopropylamines (42-65%). 相似文献
The unprecedented palladium-catalyzed C-H addition of arenes to nitriles provides moderate to excellent yields of aryl ketones or the corresponding hindered imines. The addition of a small amount of DMSO increases the yields dramatically. Both intermolecular and intramolecular reactions are successful, although the intramolecular reactions tend to be more sluggish. This novel chemistry is believed to involve palladium-catalyzed C-H activation of the arene by electrophilic aromatic substitution, followed by the unusual carbopalladation of a nitrile. Similar reactions have been successfully developed employing arylboronic acids and nitriles. A concise route to xanthones starting from cheap starting materials has been developed employing this synthetic protocol. 相似文献
A facile, efficient, and practical method for copper-catalyzed direct C-H amination of benzoxazoles with formamides or secondary amines has been developed. The system can be performed in the absence of external base and only requires O(2) or even air as oxidant. A variety of substituted benzoxazol-2-amines were synthesized with moderate to excellent yield. 相似文献
Oxime directed aromatic C-H bond activation and oxidative coupling to alkenes is reported using a cationic Rh(III) catalyst. Significantly, the method can be used to oxidatively couple unactivated, aliphatic alkenes. 相似文献
A clean and efficient method for the oxidative transformations of primary carboxamides to one-carbon dehomologated nitriles using the combination of o-iodoxybenzoic acid and tetraethylammonium bromide has been developed. This method exhibits a broad scope and is expected to be of great utility in organic synthesis. 相似文献
The ruthenium-catalyzed oxidative vinylation of thiophene-2-carboxylic acids with alkenes efficiently proceeds through directed C-H bond cleavage to give the corresponding 3-vinylated products. Similarly, benzothiophene-, benzofuran-, pyrrole-, and indolecarboxylic acids also undergo regioselective vinylation. 相似文献
Various esters were efficiently converted into the corresponding nitriles in good yields by the treatment with sodium diisobutyl-tert-butoxyaluminium hydride (SDBBA-H), followed by treatment with molecular iodine in aq ammonia. The present one-pot method is very efficient and practical for the conversion of various aromatic and aliphatic esters into the corresponding nitriles. 相似文献
The inter- and intramolecular couplings of unactivated alkenes to 3,4-dihydroquinazolines with a Rh(I) catalyst are reported. Coupling between olefins and NH-3,4-dihydroquinazoline was found to occur consecutively with heterocycle dehydrogenation in the presence of a Rh(I)/PCy3/HCl catalyst. The reaction was used to develop an effective method for the synthesis of 2-substituted quinazolines through an oxidative workup step. The regiocontrolled synthesis and Rh-catalyzed cyclization of alkene-tethered 3,4-dihydroquinazolines are also described. Applying this method, the second total synthesis of vasicoline was achieved. The key Rh-catalyzed cyclization step was made possible by the use of a rigid bicyclic phosphine ligand. The synthesis further demonstrates a challenging Cu-catalyzed amidation of an ortho-substituted aryl chloride. 相似文献
RhCl3-promoted hydroboration-oxidation reactions of representative alkenyl nitriles have been carried out. Carbanion of acetonitrile is formed from the carboncarbon heterolytic bond breaking in allyl cyanide during hydroboration. An unexpected process-trimerization of carbanion of acetonitrile has lead to the formation of 4-amino-2,6-dimethylpyrimidine. 相似文献
The intermolecular coupling of unactivated alkenes to a range of heterocycles using a Rh(I) catalyst was investigated. A variety of functional groups were incorporated into the alkene, including esters, nitriles, acetals, and phthalimide. Furthermore, the heterocycle tolerated substitution with both electron-rich and electron-deficient groups. The intermolecular coupling became possible after it was discovered that weak acids dramatically increase the rate of both the inter- and intramolecular reactions. An extensive optimization of additives was performed, and HCl.PCy(3) (Cy = cyclohexyl) and HCl.P-t-Bu(2)Et were in general found to be the best additives for the reaction. 相似文献
Not one but two: The title reaction proceeds through the dual C-H bond cleavage of both aniline and acetonitrile. The reaction affords a variety of cyano-bearing indolinones in excellent yield. Mechanistic studies demonstrate that this reaction involves a fast arylation of the olefin and a rate-determining C-H activation of the acetonitrile. 相似文献
The first general examples of palladium-catalyzed direct and selective oxidative C3-acetoxylation of indoles are presented. The mild reaction conditions (70 °C and with weak base, KOAc) in this indole C-H-acetoxylation are notable. 相似文献
The oxidative direct cyclizaion of N-methylanilines with electron-deficient alkenes involving maleimides and benzylidene malononitriles through sp(3) and sp(2) C-H bond cleavage proceeds effectively under a CuCl(2)/O(2) catalysis to provide the corresponding tetrahydroquinolines in good yields. 相似文献
Aryl triflates were transformed to aryl bromides/iodides simply by treating them with LiBr/NaI and [Cp*Ru(MeCN)(3)]OTf. The ruthenium complex also catalyzed the transformation of alkenyl sulfonates and phosphates to alkenyl halides under mild conditions. Aryl and alkenyl triflates undergo oxidative addition to a ruthenium(II) complex to form η(1)-arylruthenium and 1-ruthenacyclopropene intermediates, respectively, which are transformed to the corresponding halides. 相似文献