A highly selective synthesis of acyl isoureas and imides from readily accessible amides, isocyanides, alcohols and carboxylates based on reaction solvent selection is described. In the presence of a catalytic amount of [1,1′‐bis(diphenylphosphino)ferrocene]dichloropalladium(II) and cupric acetate, treatment of amides and isocyanides in alcohols at 60 °C provided acyl isoureas in high yields. Interestingly, when other solvents such as acetonitrile was used instead of alcohols, imides were exclusively produced in good to excellent yields via direct N‐acylation of amides with carboxylates as the acyl sources. This protocol offers an attractive alternative approach toward isoureas and imides.
Stereodefined cyclohexene and cyclopentene derivatives were prepared by the coupling of allylic alcohols and other allylic precursors with unsaturated aldehydes. These reactions are based on a multicatalytic one‐pot approach involving palladium pincer complex‐catalyzed boronation, allylation and ring‐closing metathesis reactions. This reaction sequence can be performed in an operationally simple procedure affording the cycloalkene products in high overall yields and excellent regio‐ and stereoselectivities. The presented procedure has a broad synthetic scope and high functional group tolerance, which allows the synthesis of bicyclic lactone and spirane skeletons and various substitution patterns including hydroxy, silyl, vinyl, allyl, and sulfonyl groups. The studied catalytic one‐pot reactions involve up to three individual processes performed by up to four acid‐ and transition metal‐catalyzed events. 相似文献
A new, practical synthesis of aryl and heteroaryl N‐acylureas has been developed via palladium‐catalysed carbonylation of aryl or heteroaryl halides in the presence of urea nucleophiles. A range of reactions illustrating the wide scope of this reaction was carried out under microwave irradiation, using either carbon monoxide gas in a vessel equipped with a gas inlet adapter, or molybdenum hexacarbonyl as the carbon monoxide source in standard microwave vials. The reactions proceeded in good to excellent yields. To illustrate the usefulness of this method a one‐step synthesis of the important insecticide diflubenzuron is reported. 相似文献
The palladium‐catalyzed methoxycarbonylation of 1,3‐butadiene to methyl 3‐pentenoate has been studied. Intermediates of the proposed catalytic cycle were synthesized and the elementary steps of the reaction have been investigated in detail. It is shown that the first step of the catalytic cycle, the formation of crotylpalladium complexes from 1,3‐butadiene, proceeds even at room temperature. Examination of the influence of different reaction parameters on product yield and selectivity demonstrate the importance of chelating phosphine ligands and benzoic acids as additive in order to get good results. 相似文献
A cooperative catalytic system of heterogeneous polymer‐supported bi‐metallic platinum/iridium (Pt/Ir) alloyed nanoclusters and 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spiro‐bisindane (TTSBI) enabled the facile preparation of quinazoline derivatives with low catalyst loadings and broad substrate scope under mild aerobic oxidative conditions. The ability to perform the reaction in gram‐scale and under open‐air conditions highlights the synthetic application of this cooperative catalytic system. 相似文献
A chemoselective palladium‐catalyzed anaerobic oxidation of allylic and benzylic alcohols using an α‐bromo sulfoxide as a co‐oxidant is described for the first time. The catalyst system is simple and has a long life because of the allowance of phosphane ligands under the non‐aerobic conditions. The advantages of the described method include no overoxidation of primary alcohols to carboxylic acids because of the mild conditions applied, the tolerance of oxygen‐sensitive functionalities such as a carbon‐carbon double bond, an organothio group, or a diorganoamino group and the effective preparation of α,β‐unsaturated aldehydes and ketones, resulting from the oxidation of primary and secondary allylic alcohols, since a competitive Heck reaction with the co‐oxidant does not occur. 相似文献
The formation of an amide bond via incorporation of two isocyanide units during a palladium‐catalyzed construction of the indoloquinoline ring afforded N‐substituted 6H‐indolo[2,3‐b]quinoline‐11‐carboxamides as new cytotoxic agents. The solvent and base play a key role in the selective and unprecedented synthesis of this class of amides.
A polyoxometalate with two alkyl thiol appendages, Q4[SiW11O40(SiCH2CH2CH2SH)2] (Q=ammonium salt) stabilized the formation of palladium nanoparticles. This tethered polyoxometalate–palladium binary catalyst was effective for the aerobic oxydehydrogenation of vinylcyclohexene and vinylcyclohexane to styrene as the major product via activation of the allylic, tertiary carbon‐hydrogen bond. 相似文献
Isonitriles are delicately poised chemical entities capable of being coaxed to react as nucleophiles or electrophiles. Directing this tunable reactivity with metal and non‐metal catalysts provides rapid access to a large array of complex nitrogenous structures ideally functionalized for medicinal applications. Isonitrile insertion into transition metal complexes has featured in numerous synthetic and mechanistic studies, leading to rapid deployment of isonitriles in numerous catalytic processes, including multicomponent reactions (MCR). Covering the literature from 1990–2014, the present review collates reaction types to highlight reactivity trends and allow catalyst comparison.
Redox disproportionation of benzyl alcohol to benzaldehyde and toluene catalysed by the Pd561phen60(OAc)180 (phen=1,10‐phenanthroline) giant cluster 1 under anaerobic conditions was found, whereas in an O2 atmosphere cluster 1 catalyses the oxidation of benzyl alcohol to benzaldehyde and inhibits further oxidation of the latter. A study of the AIBN‐initiated and non‐initiated oxidation of benzyl alcohol, sec‐butyl alcohol and styrene in the presence of cluster 1 revealed that cluster 1 performs three functions in the oxidation reactions: 1) catalysis of polar oxidation of the substrates with O2, 2) termination of the chains of radical oxidation, and 3) catalysis of redox disproportionation. 相似文献
Oxidation of primary and secondary aliphatic and secondary benzylic alcohols into their corresponding aldehydes and ketones was achieved in good yields with palladium catalysts using air as the reoxidant of palladium. The use of palladacycle 1 resulted in higher yields and a faster reaction than the use of Pd(OAc)2 as the palladium source. 相似文献
A Rh‐catalyzed unique and direct approach for constructing a series of 5‐arylimidazo[1,2‐c]quinazolines in moderate to excellent yields from simple and readily available 2‐arylimidazoles and 3‐phenyl‐1,4,2‐dioxazol‐5‐ones was described. This procedure proceeds with sequential ortho‐C−H bond amidation and cyclization, which represents a facile and straightforward pathway to access such frameworks.
A three‐component reaction involving isocyanides, o‐alkynyltrifluoroacetanilides, and amines for the efficient synthesis of 2‐substituted 1H‐indole‐3‐carboxamidines has been developed. The reaction proceeds through intramolecular aminopalladation of alkynes activated by isocyanide‐ligated palladium(II) species. Dioxygen acts as the sole oxidant to regenerate the active palladium(II) species.
A key discovery in the last two decades has been the realisation that gold, when prepared as supported nanoparticles, is exceptionally effective as an oxidation catalyst, particularly for the oxidation of alcohols. The catalytic efficacy is enhanced further by the alloying of gold with palladium. In this paper we study the effect of the method preparation of gold–palladium alloy nanoparticles supported on titania and investigate the activity of the materials for the selective oxidation of benzyl alcohol. We contrast impregnation and deposition–precipitation methods and demonstrate that the most active catalysts are prepared using the deposition–precipitation method. 相似文献
