An efficient palladium(II)‐catalyzed method for the synthesis of alkylated pyridine‐substituted pyrroles has been developed by a one‐pot three component reaction of β‐bromovinyl aldehydes, primary amines and 2‐alkynylpyridines in good yields. The reactions can also provide an efficient route to 2‐picolinoylpyrroles by slightly altering the reaction conditions.
An efficient alkylation method of functionalized alkyl halides under mild nickel‐catalyzed C(sp3) C(sp2) Suzuki cross‐coupling conditions is described. The features of this approach are excellent functional group compatibility, low cost nickel catalyst, and the use of a mild base. This is also the first successful example of the nickel‐catalyzed direct 2,2‐difluoroethylation or 2,2,2‐trifluoroethylation of aryl‐/heteroarylboronic acids.
An efficient and concise one‐pot strategy for the direct alkylation of quinoline N‐oxides via palladium‐catalyzed dual C H bonds activation has been developed. This methodology provides quinoline‐containing heterocyclic molecules in moderate to excellent yields.
A concise synthesis of 1‐naphthols via cyclization of o‐iodoacetophenones and methyl ketones has been realized under very mild conditions. The cyclization process is initiated by a rare copper‐catalyzed arylation of simple methyl ketones with ortho‐iodoacetophenones.
An efficient synthetic strategy for the unique class of pyrazolo[1,2‐a]cinnolines was developed through a rhodium‐catalyzed oxidative coupling of N‐aryl‐1H‐pyrazol‐5(4H)‐ones with internal alkynes. This protocol features use of the pyrazolone function in the substrate as an intrinsic directing group, hexafluoroisopropyl alcohol (HFIP) as the solvent, and mild reaction conditions as well as a wide substrate scope.
A novel and convenient palladium‐catalyzed cross‐coupling reaction of H‐phosphonate diesters with sodium arylsulfinates was developed via desulfitation in the presence of silver carbonate and tetra‐butylammonium chloride. This method is highly efficient and provides a rapid access to a broad spectrum of arylphosphonate diesters in good to excellent yields.
We disclose herein an efficient enantioselective conjugate addition reaction between coumarin‐3‐carboxylic acids and malonic acid half thioesters (MAHTs). The reaction was catalyzed by N‐heteroarenesulfonyl Cinchona alkaloid amides to afford double‐decarboxylative conjugate addition products in good yield with high enantioselectivity. The reaction of various coumarin‐3‐carboxylic acids with MAHTs gave products in high yield with high enantioselectivity.
A versatile strategy for the synthesis of fused cyclopentenones, key structural motifs in biologically relevant compounds such as indenones and indole alkaloids, has been established successfully through regioselective palladium‐catalyzed cyclization of 2‐iodoaryl allenols.
A simple and efficient domino protocol has been developed for the preparation of biologically important benzamides, 2,2‐diazidobenzofuran‐3(2H)‐ones and benzoxazolones from various structurally and electronically divergent acetophenones and ortho‐hydroxyacetophenones in the presence of molecular iodine, sodium azide and sodium bicarbonate at 100 °C in good to excellent yields.
By using N,N‐dimethylformamide (DMF) as a methylenating reagent, the copper‐catalyzed C H activation of indole was demonstrated as an efficient and facile protocol for synthesizing 3,3′‐diindolylmethane (DIM) and its derivatives. The results indicate that copper chloride was the best catalyst among the investigated transition metal salts, which affords an excellent regioselectivity and good yield when tert‐butyl hydroperoxide (TBHP) was used as an oxidant.
The first successful gold(I)‐catalyzed reaction of aryl aldehydes with trimethyl(arylethynyl)silanes to furnish bis‐alkynylated derivatives is reported. Key C C bond‐forming events involved in the catalytic cycle are analyzed.
A copper(I)‐catalysed domino transformation for the synthesis of tricyclic imidazobenzimidazole derivatives was developed. Using readily available primary propargylic amines and o‐haloarylcarbodiimides as the starting materials, a variety of substituted benzo[d]imidazo[1,2‐a]imidazoles was efficiently and selectively assembled. Further investigations indicated that the domino reaction was likely the result of a novel addition/cycloisomerisation/coupling process.
A sequential one‐pot synthesis of Michael adducts of aroylmethylidenemalonates with activated aromatics is described. The method involves treatment of trans‐2‐aryl‐3‐nitro‐cyclopropane‐1,1‐dicarboxylates with boron trifluoride etherate to form aroylmethylidenemalonates in situ and then addition of activated aromatics such as indoles, carbazole, pyrrole, thiophenes, methoxybenzenes and benzodioxole followed by a catalytic amount of indium(III) triflate to the same reaction vessel. To prove the synthetic potential of the resulting Michael adducts, one of the adducts was transformed into a pharmaceutically interesting dihydropyridazinone derivative.
A practical synthesis yielding P‐perfluoroalkylated phosphines from triarylphosphines and perfluoroalkyl iodides has been developed. The photoinduced reaction involves the substitution of aryl groups on the phosphorus atom with perfluoroalkyl groups to successfully afford P‐perfluoroalkylated phosphines. In addition, the P‐perfluoroalkylated phosphines were found to promote the Cu‐free cross‐coupling reaction of acid chlorides with terminal alkynes.
The rhodium(III)‐catalyzed aromatic C H activation/intramolecular Heck‐type reaction has been studied to synthesize spirocyclic compounds, an important class of molecules in medicinal chemistry and natural product synthesis. This approach was efficient with a variety of substituted N‐methoxybenzamides tethered to different cyclic alkenes having a 5‐, 6‐ or 7‐membered ring. This practical method affords sterically hindered o‐substituted aryl spirocycles that are valuable compounds for further functionalization to access relevant building blocks.
Copper chloride‐catalyzed aerobic oxidative annulation of N‐furfuryl‐β‐enaminones provides access to polysubstituted pyrroles and indoles. This protocol involves an unprecedented copper chloride‐catalyzed oxidative chlorination of furan and pyrrole rings with oxygen as the terminal oxidant.
A practical, nickel‐catalyzed Kumada‐type double cross‐coupling reaction of gem‐difluoroalkenes with 1,4‐ or 1,5‐di‐Grignard reagents was developed. The reaction proceeded efficiently at room temperature and a variety of cyclization products, arylmethylenecyclopentanes and arylmethylenecyclohexanes, were obtained in high to excellent yields, respectively.
