Yuki Nagashima 교수

Borylzincate was generated in situ from dialkylzinc, diboron, and metal alkoxide. Model DFT calculations showed that although the formation of borylzincate is kinetically favorable, it is thermodynamically unfavorable. Therefore, we designed a successive reaction sequence that would provide a compensating energy gain. This enabled Zn-catalyzed borylation of aryl halides and borylzincation of benzynes and terminal alkyne from diborons without the need for any cocatalyst.

We present the first trans-selective diborylation reaction of alkynes. By means of theoretical calculation-assisted reaction analysis, we designed a pseudo-intramolecular reaction of diboron, propargyl alcohol, and a base to facilitate B-B bond activation and C-B bond formation with high efficiency. This approach provides synthetically versatile and densely functionalized 4-borylated 1,2-oxaborol-2(5H)-oles (vinyldiboronates) in a straightforward manner. Detailed computational analysis showed th

We present the first quadruple borylation reaction of terminal alkynes, affording functionalized 1,1,2,2-tetrakis(boronate) derivatives in a chemo-/regioselective manner. The methodology is operationally simple and a novel B-B bond activation without the need for a transition-metal catalyst.

Abstract A new protocol has been designed for the in situ generation of unstable Si−Zn species through the reaction of dialkylzinc, phosphine, and silylborane (Si−B). Successive reactions with various terminal alkynes using this protocol enabled highly controllable regio‐/stereo‐/chemoselective silylzincation and silaboration on demand without the need for a transition‐metal catalyst.

A rhodium(III) complex bearing a 1,3-bis(ethoxycarbonyl)-substituted or an unsubstituted cyclopentadienyl ligand (CpE or Cp) significantly accelerates a variety of oxidative C–H bond functionalization reactions. However, the driving force of the acceleration compared with a conventionally used Cp*Rh(III) complex has not been elucidated. Herein, we performed density functional theory (DFT) calculations of the rhodium(III)-catalyzed oxidative C–H bond olefination and annulation reactions using Cp*

It has been established that an unsubstituted cyclopentadienyl (Cp) Rh(III) complex is an effective catalyst for the oxidative <i>ortho</i>-olefination of phenyl carbamates with both acrylates and styrenes under mild conditions. In addition, diolefination of a protected BINOL (1,1'-binaphthalene-2,2'-diol) proceeded in high yields and disubstituted acrylates could participate in this catalysis. Experimental and theoretical mechanistic studies elucidated that an electron-deficient nature of the u

We have developed photoboosted stannylation reactions of terminal alkynes (linear-selective hydrostannylation) and fluoroarenes (defluorostannylation), in which the stannyl anion is photoexcited to an excited triplet (T₁) stannyl diradical species. This unprecedented T₁-stannyl diradical species shows completely different reactivity and selectivity from those of stannyl anions and stannyl radicals. This methodology is operationally simple, has broad functional group toleran

The fluoranthene skeleton is a structure often found in natural products and fluorescent materials, and thus developing an operationally simple method for diversity-oriented fluoranthene synthesis is an important research topic in organic synthesis. However, existing synthetic methods require harsh reaction conditions or limited substrate applicability or both. Here, we report the room temperature synthesis of substituted fluoranthenes and azafluoranthenes through the cationic Rh(I)/H8-BINAP com

Silyl radicals are valuable species to prepare diverse organosilicon compounds. However, unlike stable tertiary silyl radicals, the use of secondary silyl radicals has been problematic in silylation reactions due to their instability. Here, we present photocatalytic in situ generations of both secondary and tertiary silyl radicals by one-electron oxidation of ate complexes, formed from silylboranes and an alkoxide cocatalyst, achieving highly efficient hydrosilylation and deuterosilylation of el

It has been established that a cationic gold(I)/PCy3 complex catalyzes the intramolecular cascade reaction of enediyne-carbonyls via benzopyrylium intermediates giving pentacyclic compounds, bearing five or six stereocenters with high yields and diastereoselectivity. In this cascade reaction, [3 + 2] annulation, carbenoid transfer, and C–H insertion proceed in one-pot. The DFT calculation revealed that both the [3 + 2] and [4 + 2] annulations proceed via the same gold(I) carbenoid, produced by t

Abstract A new protocol has been designed for the in situ generation of unstable Si−Zn species through the reaction of dialkylzinc, phosphine, and silylborane (Si−B). Successive reactions with various terminal alkynes using this protocol enabled highly controllable regio‐/stereo‐/chemoselective silylzincation and silaboration on demand without the need for a transition‐metal catalyst.

We have developed a visible-light-induced method to photolyze digermanes through single-electron oxidation using a photocatalyst, in contrast to direct excitation, to generate germyl radicals and achieve the hydro/deuteriogermylation of alkenes. This protocol allows the previously elusive incorporation of the small trimethylgermyl group and deuterium, metabolically stable bioisosteres of <i>tert</i>-butyl and hydrogen, respectively, making this approach attractive in not only organic synthesis b

Abstract Axially chiral styrene‐carboxylic esters were synthesized in high yields with excellent enantioselectivity by the cationic rhodium(I)/H 8 ‐BINAP complex‐catalyzed chelation‐controlled [2+2+2] cycloaddition reactions of 1,6‐ and 1,7‐diynes with 1,3‐enyne‐carboxylic esters. The diastereo‐ and enantioselective synthesis of C 2 symmetric axially chiral cis and trans ‐stilbene‐dicarboxylic esters was also achieved by the double [2+2+2] cycloaddition reactions of two molecules of the 1,6‐diyn