A unique one‐pot synthesis of cyclic cis‐1,2‐amino alcohols from trans‐1,2‐azido alcohol precursors was developed. The key step is highlighted by the stereoselective reduction of the cyclic α‐alkoxy imines, which could be prepared from the corresponding azides by ruthenium catalysis under photolytic conditions. Remarkably, this unprecedented reaction pathway offers a stereodivergent access to structurally diverse cyclic 1,2‐amino alcohols.
This paper discloses an iodine‐mediated C H thiolation strategy for introduction of dithiocarbamates onto imidazoheterocycles under mild conditions. Imidazole derivatives, including imidazopyridines, imidazothiazoles, and benzoimidazoles, were well tolerated to afford diverse imidazoheterocycles‐dithiocarbamates compounds. These compounds are expected to be significant for drug discovery.
The efficient simultaneous activation of cyclohexenones or simple alkyl acyclic enones and 2‐hydroxynitrostyrenes was realized by using a prolinol thioether catalyst. Thus, a highly chemo‐, diastereo‐ and enantioselective synthesis of functionalized tetrahydroxanthenones and chromanes with up to three contiguous stereocenters was developed.
Copper‐catalyzed ring‐opening reactions of cyclic 1,2‐sulfamidates with a wide range of Grignard reagents have been investigated. The use of lithium chloride as an additive is essential to activate C O bond cleavage. The reaction represents highly regio‐ and stereoselective, and thus allows for efficient synthesis of enantioenriched α‐branched benzylamine derivatives. Furthermore, we demonstrated that the products are potential to be used as building blocks for the preparation of wide range of nitrogen‐containing heterocycles.
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.
1‐Bromo‐2‐(cyclopropylidenemethyl)benzenes react with 2‐alkynylphenols under palladium catalysis, leading to indeno[1,2‐c]chromenes in moderate to good yields. The molecular complexity and diversity can be introduced efficiently from easily available starting materials.
Palladium nanoparticles stabilized with tris‐imidazolium tetrafluoroborates catalyze the stereoselective hydrosilylation of internal alkynes in a dry inert atmosphere to give (E)‐vinylsilanes in excellent yields. In the presence of controlled amounts of water a transfer hydrogenation reaction takes place with the formation of (Z) ‐ alkenes or the corresponding alkanes.
The rhodium(I)‐catalyzed reaction between arylboronic esters and excess 1,2‐dichloroethene selectively afforded (2‐chlorovinyl)arenes. Double arylation yielding 1,2‐diarylethenes was observed when 1,2‐dibromoethene was reacted with 2.5 equivalents of arylboronic acid.
A rhodium(III)‐catalyzed amidation between benzoic acids and isocyanates via direct functionalization of an ortho C H bond followed by intramolecular cyclization is described. This cascade cyclization affords N‐substituted phthalimides in one step in 26–91% yields. The reaction is highly atom‐economical, since no theoretical waste except for water is generated in the reaction.
The ring‐opening of N‐tert‐butanesulfinylethynylaziridines with lithium tris(dimethylphenylsilyl)zincate is reported. The reaction is demonstrated to be both stereoselective and stereospecific and to proceed through an anti‐SN2′ process. Further deprotection of the nitrogen atom under mild conditions allows access to 4‐amino‐1‐(dimethylphenylsilyl)allenes with high yields and levels of stereoselectivity.
We disclose the highly diastereoselective combination of monoamine oxidase‐catalyzed oxidation of meso‐pyrrolidines and aza‐Friedel–Crafts reactions in aqueous buffer to give valuable enantioenriched 2‐substituted pyrrolidines in a formal double C H activation process. A range of secondary as well as tertiary amines were shown to be suitable substrates for the biocatalytic oxidation and subsequent addition of a variety of C‐nucleophiles.
A phosphane‐catalyzed [3+3] annulation of azomethine imines with ynones has been developed. Under mild reaction conditions, the reaction proceeds smoothly to afford tricyclic dinitrogen‐fused heterocyclic compounds in moderate to excellent yields with moderate to excellent stereoselectivies. Using a chiral phosphine as the catalyst, the reaction could work to give the cycloadduct in moderate yield with moderate enantioselectivity.
A potassium hydroxide/dimethyl sulfoxide (KOH/DMSO) superbase‐promoted method for the synthesis of 2‐substituted benzothiophenes has been developed via photoinduced intermolecular annulation of 2‐halothioanisoles with terminal alkynes at ambient temperature. The present protocol uses commercially available 2‐halothioanisoles as substrates and visible light as energy force, which offers a wide range of benzothiophenes regioselectively in moderate to good yields. Such a facile and effective transformation will provide an environment‐friendly approach to the synthesis of benzothiophene derivatives.
A novel and efficient domino process has been developed for the synthesis of 1,4‐benzoxazepine derivatives from a range of readily accessible N‐tosylaziridines, 2‐iodophenols and isocyanides. This process involves the aziridine ring‐opening reaction with 2‐iodophenol, followed by a palladium‐catalyzed isocyanide‐insertion reaction. This regioselective and high‐yielding transformation could be extended to its application for the synthesis of natural products and biologically interesting heterocycles.
Boron trifluoride nitrile complexes promote oxidative [2+2+1] annulations of alkynes, nitriles and N‐atoms from iminoiodanes to give the corresponding 2,4‐disubstituted and 2,4,5‐trisubstituted N‐tosylimidazoles in moderate to good yields with high regioselectivities.
