Jun Takaya

Tridentate PSiP pincer-type palladium complex-catalyzed hydrocarboxylation of allenes under carbon dioxide to give synthetically useful beta,gamma-unsaturated carboxylic acids was developed. This novel CO2-fixation reaction is thought to proceed through the catalytic generation of sigma-allyl palladium species via hydropalladation of allenes, followed by its regioselective nucleophilic addition to CO2 in the presence of an appropriate reducing agent. The reaction is successfully applied to vario

The copper(I)-catalyzed carboxylation reaction of aryl- and alkenylboronic esters proceeded smoothly under CO(2) to give the corresponding carboxylic acid in good yield. This reaction showed wide generality with higher functional group tolerance compared to the corresponding Rh(I)-catalyzed reaction.

Bis(boronate) compounds have been attracting much attention as versatile building blocks for concise synthesis of complex molecules because these compounds enable multiple C–C bond formations and functionalizations at the C–B bonds. Transition metal-catalyzed diboration reactions of unsaturated hydrocarbons with diborons have been utilized as a straightforward and highly useful method for the synthesis of bis(boronate) compounds. This perspective article will summarize recent development in subs

Efficient synthesis and catalysis of a series of palladium complexes having a group 13 metalloligand (Al, Ga, In) are reported utilizing 6,6″-bis(phosphino)terpyridine as a new scaffold for Pd-E bonds (E = Al, Ga, In). Systematic investigation revealed unique characteristics of the Al-metalloligand in both structure and reactivity, which exhibited the highest catalytic activity for hydrosilylation of CO₂ ever reported (TOF = 19 300 h^-1). This study demonstrated fine-tuning

Recent development in catalytic application of transition metal complexes having an M-E bond (E = main group metal or metalloid element), which is stabilized by a multidentate ligand, is summarized. Main group metal and metalloid supporting ligands furnish unusual electronic and steric environments and molecular functions to transition metals, which are not easily available with standard organic supporting ligands such as phosphines and amines. These characteristics often realize remarkable cata

The efficient synthesis of various diborylalkenes such as 1,1-, trans-1,2-, and cyclic 1,2-diborylalkenes from alkenes and diboron was achieved for the first time. Selective preparation of di- and monoborylalkenes was also realized by the appropriate choice of reaction conditions. The reaction was found to proceed via a new mechanism of dehydrogenative borylation through a monoborylpalladium complex bearing an anionic PSiP-pincer ligand as a key intermediate, which realized the efficient borylat

Studies are described that reveal the steps of the anti-Markovnikov hydroamination of vinylarenes with alkylamines catalyzed by Ru(COD)(2-methylallyl)2, bis(diphenylphosphino)pentane, and TfOH. Treatment of the catalyst components with an excess of styrene under the catalytic reaction conditions afforded a new ruthenium eta6-styrene complex with an ancillary tridentate PCP ligand. This ruthenium complex was active as catalyst for the hydroamination of styrene with morpholine to give the anti-Mar

An efficient one-to-one coupling reaction of atmospheric pressure carbon dioxide with 1,3-dienes is realized for the first time through PSiP-pincer type palladium-catalyzed hydrocarboxylation. The reaction is applicable to various 1,3-dienes including easily available chemical feedstock such as 1,3-butadiene and isoprene. This protocol affords a highly useful method for the synthesis of β,γ-unsaturated carboxylic acid derivatives from CO(2).

An alkyne moiety is activated efficiently with a [W(CO)6] or [ReBr(CO)5] catalyst in the presence of an amine functionality in the title reaction of N-(2-alkynylphenyl)amines. The resulting ammonium ylides undergo rearrangement to form a variety of N-fused polycyclic indole derivatives (see scheme; n=1,2; R=alkyl, Ph).

Synthesis and structural analysis of an unprecedented η2-Si−H complex of mononuclear Pd(0) was achieved utilizing bis(o-phosphinophenyl)silane as a PSiP pincer-type scaffold for the first time. This complex showed dynamic behavior in its reaction with an allene, involving a reversible oxidative addition/reductive elimination sequence of a C(sp3)−Si bond at room temperature. This system will be useful as a synthetic equivalent of highly reactive hydrido- and (σ-allyl)palladium species.

Efficient, phosphine-directed ortho C-H borylation of arylphosphine derivatives was achieved using Ru catalysts for the first time. The reaction is applicable to various tertiary arylphosphine and arylphosphinite derivatives to give (o-borylaryl)phosphorus compounds in high yields. This reaction enables easy access to a variety of functionalized phosphine ligands and ambiphilic phosphine boronate compounds, thus realizing a new late-stage modification of phosphorus compounds.

An efficient, regioselective synthesis of fluorine-substituted arylboronic esters was achieved through fluorine-controlled C-H borylation of arenes with diboron catalyzed by a PSiN-platinum complex. The promising utility of the PSiN-platinum catalyst and its unique regioselectivity were demonstrated for the first time, which would complement the well-developed Ir-catalyzed C-H borylation.

Reactions of bis(o-(diphenylphosphino)phenyl)methylsilane with M(PPh(3))(4) (M = Ni, Pd, Pt) were investigated. When M = Ni or Pd, synthesis and isolation of η(2)-(Si-H) complexes of mononuclear Ni(0) and Pd(0) were achieved for the first time as frozen intermediates for oxidative addition of the Si-H bond. Structural analysis by X-ray and NMR spectroscopy disclosed that their η(2)-(Si-H) structures were maintained in both solid and solution states and coordination of the Si-H bond to the metal

On treatment of silyl enolates and an N,O-hemiacetal, derived from trifluoroacetaldehyde ethyl hemiacetal and p-anisidine, with GaCl(3) (0.2 equiv) and C(6)H(5)COCl (0.2 equiv) in propionitrile, Mannich-type reaction took place smoothly to afford beta-amino-beta-trifluoromethyl carbonyl compounds in high yields.

Lovely lactams: Synthetically useful γ-lactam derivatives have been prepared through the unique title transformation. By utilizing the characteristic property of the molybdenum complex, two kinds of products (both of which have rarely been obtained by reactions catalyzed by late transition metals) were obtained selectively by adjusting the reaction conditions (see scheme). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-review