A copper‐catalyzed cascade reaction involving trifluoromethylation of acrylamides coupled with ring closure and indole dearomatization is reported. This facile transformation was highly regioselective and proceeded under mild conditions, allowing efficient access to trifluoromethyl‐substituted spiro[indole‐3,3′‐pyrrolidine] derivatives, which are of increasing interest to the pharmaceutical industry.
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 highly efficient dearomatization reaction of α‐substituted β‐naphthols with excellent chemoselectivity and regioselectivity has been developed. Mechanistic studies demonstrated that the dearomatized alkylation product is the thermodynamically more stable compound. The etherification product could be further transformed to the dearomatization product.
Hydrogenation of carbon dioxide to formate was achieved using copper (Cu) catalysts in the presence of strong organic bases including amidines and guanidines. Specifically, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) proved to be effective for the transformation of a 1:1 mixture of hydrogen and carbon dioxide into its formate salt under increased pressure in the presence of various Cu(I) and Cu(II) salts at 100 °C. A novel complex derived from copper iodide and DBU equally promoted the same reaction, indicating that DBU–Cu species are involved as real catalysts in this hydrogenation.
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.
A novel, direct and simple methodology to gain access to α,β‐disubstituted conjugated enones from α‐allenols in a sustainable metal catalysis context, considering the inexpensiveness and environmentally friendliness of iron(III) species and protons, has been developed.
A transition metal‐free direct arylation of 2‐substituted cyanoacetates with diaryliodonium salts was developed. With this approach, a wide range of α‐tolunitrile derivatives has been synthesized in good to excellent yields of 45–92%. Furthermore, the practicability of this approach is further manifested in the synthesis of a related bioactive agent of glutarimide.
A new palladium‐catalyzed route to 3‐hydroxy‐4‐arylcyclopentanones and 4‐arylcyclopentenones in a diastereo‐ and enantioselective manner by a Heck–Matsuda desymmetrization was achieved from the commercially available meso cis‐4‐cyclopentene‐1,3‐diol. This method is highly practical, mild, high yielding and is carried out under “open vessel” conditions. Protected and unprotected substrates provide distinct products bearing considerable value as synthetic scaffolds for the synthesis of natural and unnatural bioactive compounds containing a five‐membered ring.
The paper describes the oxidative Heck arylation of various allylic amines using arylboronic acids for the preparation of tetrasubstituted alkenes. As oxidant the commercially available 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) is used and coupling reactions occur under very mild conditions at room temperature. The densely substituted alkenes are formed in good to excellent yields with complete control of the diastereoselectivity. Substrate scope with respect to the allylic amine and the arylboronic acid is investigated.
A gold(I)‐catalyzed cascade [3,3]‐propargylic rearrangement and [4+2] cycloaddition reaction of 2‐vinylindoles with propargylic esters is reported. The reaction leads to the synthesis of highly substituted tetrahydrocarbazole derivatives in high yields and diasteroselectivities. Furthermore, a preliminary screening for an asymmetric version of this reaction is described.
A transition metal‐free and efficient method for the synthesis of 3‐alkynylpyrrole‐2‐carboxylates from diynones and glycine esters or 2‐aminoacetophenone hydrochloride has been developed. This transformation provides a large range of substituted pyrroles in good to excellent yields with the elimination of water as the only by‐product. The detailed mechanistic studies elucidated that this transformation involves a Michael addition/intramolecular cyclodehydration process.
