Research

Our main focus is on Organic Synthesis, developing new approaches to molecular skeletons, and building complexity rapidly yet selectively. In our laboratory, we develop such transformations catalyzed by metal salts and organocatalysts to achieve the above goals. Our interests include element-element coupling/addition reactions (element being -B, -Si, -F, -C, -N, -X, etc.), Redox chemistry involving radicals, and so on. 

Nickel(0)-Catalyzed Cycloaddition Reactions

Our research group is dedicated to advancing nickel(0)-catalyzed cycloaddition reactions as powerful tools for the efficient and selective construction of complex organic molecules. We focus on developing robust catalytic systems, elucidating their mechanisms, and expanding their utility in modern synthetic chemistry.

A key area of our work involves the exploration of Ni(COD)(DQ)—a bench-stable nickel(0) complex—as a catalyst for the reductive coupling of aldehydes with alkynes and ynamides, yielding silylated allyl alcohols with high regioselectivity and excellent efficiency. Using a combination of mass spectrometry and DFT studies, we have uncovered detailed mechanistic pathways that underpin this transformation. Notably, Ni(COD)(DQ) exhibits long-term stability and high catalytic activity, making it an accessible and user-friendly platform for Ni(0) catalysis. We also developed a modular approach for the in situ generation of Ni(NHC)(EDO) complexes, facilitating rapid screening for enantioselective applications.

Our research further extends to [2+2+2] cyclotrimerization of 1,3-diynes, enabling the regioselective synthesis of hexa-substituted benzenes (HSBs)—compounds of interest in materials science and pharmaceutical chemistry. This methodology accommodates diverse substituents and offers mechanistic clarity through combined experimental and computational studies.

We have also pioneered a diastereoconvergent reductive coupling of heteroatom-substituted allyl substrates with aldehydes to generate syn-chromanols via a [2+2+1] oxidative cycloaddition mechanism. This transformation is notable for its broad substrate scope and practical relevance, as demonstrated in formal syntheses of biologically significant molecules such as CP-199.330, CP-199.331, and CP-85.958.

Collectively, our work aims to broaden the scope and understanding of nickel(0)-catalyzed cycloadditions, offering new synthetic strategies and mechanistic insights that are valuable across academic and industrial settings in organic synthesis.

Metal-Catalyzed Introduction of Main Group Functionalities & Their Reactivity

We are interested in introducing Main group functionalities that are challenging on various systems. We employ transition metals and organocatalysts to achieve such transformations.

Our interest was in developing the protoboration of 1,3-diynes as a platform for the iterative functionalization of various groups on enynes and dienes. An operationally simple, regioselective protoboration of 1,3-diynes using a mixed diboron reagent and Cu(I)/phosphine catalyst provided enynylboronates and 1,4-diboryl-1,3-dienes in good yields. The iterative coupling capabilities of the products have been demonstrated along with other downstream transformations, offering a range of value-added skeletons. A carbo-/protoboration of boryl enynes provides access to an array of penta- and hexasubstituted diboryl dienes in a chemo-, regio- and stereoselective manner. All six positions of the dienes can be manipulated using this methodology. The hexasubstituted diene boronates adopt a skew conformation. An iterative Suzuki coupling of the products provided highly conjugated trienes and tetraenes.

1,n-Zwitterion Generation and Reactivity

Our research explores the generation and reactivity of 1,n-zwitterionic species as a platform for the development of novel catalytic transformations that enable simultaneous multifunctionalizations of organic substrates. By leveraging the versatility, stability, and commercial accessibility of organophosphorus compounds, we aim to expand the synthetic potential of main-group element catalysis in organic chemistry.

We developed an organophosphorus-catalyzed borylative ring-opening/allylation of vinylcyclopropanes (VCPs) to access δ-hydroxy esters with high stereoselectivity. These intermediates were efficiently lactonized to yield densely substituted δ-valerolactones, showcasing excellent functional group tolerance and operational simplicity. Mechanistic investigations, including ³¹P NMR studies, revealed the involvement of a phosphonium zwitterionic species, providing mechanistic clarity and synthetic opportunity. The utility of the intermediate allyl boronates further highlights the versatility of this approach.

In parallel, we developed a [3+2] cycloaddition strategy between VCPs and activated coumarins under palladium catalysis, offering access to cyclopenta[c]chromanones bearing up to four contiguous stereocenters with excellent diastereocontrol. Mechanistic studies, supported by density functional theory (DFT) calculations, indicate a thermodynamically controlled pathway driving the observed selectivity.

Additionally, we established a Pd(0)-catalyzed (3+3) annulation between VCPs and boronic acid derivatives, leading to the efficient synthesis of vinyltetralones under mild conditions. This reaction accommodates a broad range of functional groups and provides access to structurally diverse scaffolds. The synthetic value of these vinyltetralones was further demonstrated through downstream functionalization.

Overall, our research contributes to the development of main-group and transition-metal catalyzed methodologies that harness zwitterionic intermediates for complex molecule construction. These efforts advance the field of synthetic organic chemistry by offering new strategies for achieving chemo-, regio-, and stereoselective transformations with broad functional group compatibility.

Aromaticity and Soft Materials with Optoelectronic Properties

The cyclic non-benzenoid compounds show interesting aromaticity characteristics, which impart special molecular and optoelectric properties. We have contributed to the understanding of their mechanism of action using computational and experimental techniques.