4‐(Dimethylamino)pyridine‐Catalyzed (3+2) Annulation of Pyrazoledione‐Derived Morita–Baylis–Hillman Carbonates with 2‐Arylideneindane‐1,3‐diones: An Access to Dispirocyclic Compounds

Interrupted Michael Reaction: Sulfophosphinoylation of α,β-Unsaturated Ketones Catalyzed by Phosphine

An efficient method for phosphine-catalyzed sulfophosphinoylation of α,β-unsaturated ketones for synthesis allylic organophosphorus compounds has been reported, in which α,β-unsaturated compounds acting as zwitterions react with electrophiles and nucleophiles to form a C-P bond and a C-O bond and obtain allylic organophosphorus with high regio- and stereoselectivity in moderate to excellent yields.

Chemodivergent Parallel Kinetic Resolution of Paracyclophanes: Enantiomer Fishing with Different Substrates

An unprecedented chemodivergent strategy for parallel kinetic resolution (PKR) is disclosed through which two planar chiral products bearing different structures were simultaneously afforded with opposite stereoselectivities. Two achiral esters are activated by one single chiral N-heterocyclic carbene (NHC) catalyst to react with the different enantiomers of the racemic imine substrate in a parallel fashion. Two products bearing distinct structures and opposite stereoselectivities are respectively afforded from the same reaction system in good to excellent yields, enantio- and diastereoselectivities. Control experiments and kinetic studies are carried out to probe the kinetic and dynamic properties during the reaction progress. The planar chiral pyridine and lactam products show interesting applications in both asymmetric synthesis and pesticide development.

DMAP Catalyzed Ring-Opening/Cycloaddition of Vinyl Oxiranes with Activated Ketone Compounds to Construct the 1,3-Dioxolane Skeletons

The present work develops a DMAP-catalyzed [3 + 2] cycloaddition of vinyl oxiranes with activated ketone compounds, affording dioxolane derivatives with moderate to excellent yields. This approach represents the first Lewis base (LB)-catalyzed ring-opening reaction of vinyl epoxides, simultaneously providing a rare oxygen-containing active intermediate in this field. The gram-scale preparation and facile derivatization of the cycloadduct highlight the significant synthetic potential of this strategy.

DMAP-Catalyzed [4+3] Spiroannulation of Pyrazolone-Derived Morita-Baylis-Hillman Carbonates with N-(o-Chloromethyl)aryl Amides to Forge Spiro[pyrazolone-azepine] Scaffolds

A novel DMAP-catalyzed [4+3] spiroannulation of pyrazolone-derived Morita-Baylis-Hillman carbonates with N-(o-chloromethyl)aryl amides was developed. This reaction led to the assembly of medicinally relevant pyrazolone and azepine nuclei into a structurally new spirocyclic scaffold, and a diverse array of spiro[pyrazolone-azepine] products were afforded in good to excellent yields (up to 93%) with a wide substrate scope (23 examples) under mild conditions. Moreover, a gram-scale reaction and product transformations were conducted, which further increased the diversity of products.

Silver/chiral pyrrolidinopyridine relay catalytic cycloisomerization/(2 + 3) cycloadditions of enynamides to asymmetrically synthesize bispirocyclopentenes as PDE1B inhibitors

Significant progress has been made in asymmetric synthesis through the use of transition metal catalysts combined with Lewis bases. However, the use of a dual catalytic system involving 4-aminopyridine and transition metal has received little attention. Here we show a metal/Lewis base relay catalytic system featuring silver acetate and a modified chiral pyrrolidinopyridine (PPY). It was successfully applied in the cycloisomerization/(2 + 3) cycloaddition reaction of enynamides. Bispirocyclopentene pyrazolone products could be efficiently synthesized in a stereoselective and economical manner (up to >19:1 dr, 99.5:0.5 er). Transformations of the product could access stereodivergent diastereoisomers and densely functionalized polycyclic derivatives. Mechanistic studies illustrated the relay catalytic model and the origin of the uncommon chemoselectivity. In subsequent bioassays, the products containing a privileged drug-like scaffold exhibited isoform-selective phosphodiesterase 1 (PDE1) inhibitory activity in vitro. The optimal lead compound displayed a good therapeutic effect for ameliorating pulmonary fibrosis via inhibiting PDE1 in vivo.

Asymmetric [3 + 2] spiroannulation of pyrazolone-derived Morita–Baylis–Hillman carbonates with alkynyl ketones: facile access to spiro[cyclopentadiene-pyrazolone] scaffolds

A tertiary amine-catalyzed asymmetric [3 + 2] spiroannulation reaction of pyrazolone-derived Morita–Baylis–Hillman carbonates with alkynyl ketones was achieved under mild conditions. This protocol offers a facile approach to chiral spiro[cyclopentadiene-pyrazolone]...

Organocatalytic (5+1) benzannulation of Morita–Baylis–Hillman carbonates: synthesis of multisubstituted 4-benzylidene pyrazolones

DABCO-catalyzed (5+1) cycloaddition of MBH carbonate undergoes an α-double deprotonation pathway to de novo assemble the benzene ring.