The first example of enantioselective nitronate protonation following Michael addition of a carbon nucleophile to an α,β,β‐trisubstituted nitroalkene is reported. An N‐sulfinylurea catalyst was employed to catalyze the addition of a variety of 3‐substituted pyrazol‐5‐one nucleophiles to trisubstituted nitroalkenes incorporating an oxetane or azetidine ring at the β‐position. The nitroalkane‐pyrazolone adducts were obtained with good yield and enantioselectivity. Furthermore, the Michael addition products can be reduced to the corresponding enantioenriched amines with minimal loss of enantiomeric purity.
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.
We report the palladium(II)‐catalyzed aerobic oxidative coupling of isocyanides with various (2‐aminophenyl)azoles using air as the stoichiometric oxidant. A diverse range of medicinally valuable azolo[c]quinazolines was obtained by this new approach.
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.
We describe a most straightforward synthetic method for preparing neurokinin‐1 (NK1) receptor antagonist derivatives by asymmetric hydrogenation of 3‐amido‐2‐arylpyridinium salts using dinuclear iridium complexes with enantiopure diphosphine ligands, affording the corresponding chiral piperidines in high cis‐diastereoselectivity (>95:5) and moderately high enantioselectivity (up to 86%). Deprotection treatments afforded the NK‐1 receptor antagonist (+)‐CP‐99,994 (83% ee). In addition, we observed unique additive effects of 10‐camphorsulfonic acid in the asymmetric hydrogenation of 3‐amido‐2‐arylpyridinium salts.
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 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.
