Gold-catalyzed cyclization of 1,5-diynesw ith ketones as reagents and solvent provides diversely substituted vinyl ethers under mild conditions. The regioselectivity of such gold-catalyzed cyclizations is usually controlled by the scaffold of the diyne. Herein, we report the first solvent-controlled switchingo fr egioselectivity from a6 -endo-dig-to 5endo-dig-cyclization in these transformations,p roviding fulvene derivatives. With respectt ot he functional-group toler-ance, aryl fluorides, chlorides, bromides,and ethers are tolerated. Furthermore, the mechanism and selectivity are put to scrutinyb ye xperimental studies and at hermodynamic analysis of the product. Additionally,6 -(vinyloxy)fulvenesa re a hitherto unknown class of compounds. Theirr eactivity is briefly evaluated, to give insights into their potential applications.[ + + ] Crystallographic investigation;T heoreticali nvestigation Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.
Palladium-catalyzed cross-coupling reaction of arylboronic acids with acid chlorides at room temperature under phosphine-free conditions affords the corresponding aromatic ketones in excellent yields within short times. This synthetic method overcomes common disadvantages of Friedel-Crafts acylation procedures and is compatible with both electron-donating and electronwithdrawing substituents on the aryl ring of the acyl chlorides.
This study describes the first para-selective palladium-catalyzed alkenylation of tertiary amines. This regioselective C-H activation was conducted without any chelation moieties. A series of olefins were reacted under mild reaction conditions at 60 °C, and the corresponding products were obtained in good yields with high selectivity.
An efficient protocol was developed for the nano CoCuFe 2 O 4 -catalyzed C-N and C-S bond formation. By this catalytic system, both amine and sulfide-based structural motifs were formed efficiently in aryl halide-free route. The amination reaction of phenyl boronic acid with various types of amines was conducted under ligand-free conditions, in ethanol as a green solvent at 60°C. Unsymmetrical diaryl/aryl alkyl sulfide synthesis via the coupling reaction of arylboronic acids with thiols was also conducted. The nano cobalt-copper ferrite was used as a heterogenous efficient, inexpensive, magnetically separable and recyclable catalyst that can be used for several cycles.
This is the first study of samarium powder catalyzed cyanation reaction of aryl halides, bearing electron‐withdrawing and electron‐releasing substituents, in the presence of NaCN to afford corresponding benzonitriles in high yields. This protocol takes the advantage of being done in the absence of additive, ligand and precious transition metals such as palladium.
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