Yoshikazu Horino

Au(I)-Catalyzed Cycloisomerizations Terminated by sp3 C-H Bond Insertion

The gold(I)-catalyzed cycloisomerization of 1,5-enynes and 1,4-allylallenes to tetracyclododecane and tetracyclotridecane derivatives, respectively, is reported. Complexation of the cationic gold(I) complex to either the alkyne or allene moiety induces an intramolecular addition of the alkene, leading to a gold(I)-stabilized carbenoid intermediate. This intermediate undergoes a formal sp(3) C-H insertion to generate the tetracyclic adduct. A series of deuterium labeling experiments showed that the C-H functionalization step proceeds with an inverse kinetic isotope effect.

Et3B-promoted, Pd(0)-catalyzed allylation of active methylene compounds with allylic alcohols

Abstract Triethylborane promotes the Pd(0)-catalyzed allylation of active methylene compounds (Meldrum’s acid and malonates) with a variety of allylic alcohols. The reaction proceeds smoothly at room temperature and provides the allylation products in good yield.

Et3B–Pd-promoted allylation of benzaldehyde with allylic alcohols

In the presence of Pd(OAc)2 (0.05 equiv.) and PPh3 (0.1 equiv.), triethylborane promotes a variety of allyl alcohols to undergo allylation of benzaldehyde to provide homoallyl alcohols in good yield.

Et 3 B-promoted, Pd-catalyzed C -allylation of o -hydroxyacetophenone and its derivatives with allyl alcohols

Triethylborane promotes the Pd-catalyzed selective C-diallylation of o-hydroxyacetophenone and C-monoallylation of o-hydroxypropiophenone with a variety of ally alcohols. The reaction proceeds smoothly at 25–50°C and provides the allylation products in excellent yields.

Allylation of aldehydes via Umpolung of π-allylpalladium(II) with triethylborane

Abstract Triethylborane induces allylic substrates (benzoates, phenyl ethers, benzyl ethers, but not halides) to undergo allylation of aldehydes in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium(0). The reaction proceeds via Umpolung of π-allylpalladium.

Efficient synthesis of 4-ethenylidene-2-oxazolidinones via palladium-catalyzed aminocyclization of 2-butyn-1,4-diol biscarbamates

4-Ethenylidene-2-oxazolidinones 2, 6, and 9 are prepared in reasonable yields by the reaction of 2-butyn-1,4-diol biscarbamates in the presence of catalytic amounts of Pd2(dba)3·CHCl3 (0.005 equiv) and triethylamine (0.1 equiv). The allenic three carbons are not aligned straight, but considerably distorted (173.6°); the enamine double bond is reactive toward unsaturated amides (providing 4) and methyl vinyl ketone (providing 10).

Efficient Entry to Tetrahydropyridines: Addition of Enol Ethers to Allenesulfonamides Involving a Novel 1,3‐Sulfonyl Shift

Heating at 70–100°C is all that is needed to induce a novel 1,3-sulfonyl shift in the reaction of N-allenesulfonamides with enol ethers [Eq. (a)]. Tetrahydropyridine derivatives are obtained in excellent yields and with high stereoselectivities.

Pd-Catalyzed Three-Component Reaction of 3-(Pinacolatoboryl)ally Acetates, Aldehydes, and Organoboranes: A New Entry to Stereoselective Synthesis of (Z)-anti-Homoallylic Alcohols.

The Pd-catalyzed three-component reaction of 3-(pinacolatoboryl)allyl acetates, aldehydes, and organoboranes is described. The reaction is initiated by the formation of an allylic gem-palladium/boryl intermediate, which then undergoes allylation of aldehydes by allylboronates followed by a coupling reaction of in situ generated (Z)-vinylpalladium acetates with organoboranes to provide the (Z)-anti-homoallylic alcohols with high levels of diastereoselectivity and alkene stereocontrol.

Relay catalysis using a gold(I) complex/Brønsted acid binary system for the synthesis of bezoxasiloles

A strategy for the synthesis of synthetically useful benzoxasilole derivatives by combining a gold(I) complex/Bronsted acid binary system and a temporary silicon tether method has been developed that involves relay catalytic cascade intramolecular allylation of alkynes by a gold(I) complex and addition of silanols to enones by a Bronsted acid.

Practical and Convenient Synthesis of 1,6-Di- or 1,2,5,6-Tetra-arylhexa-1,3,5-trienes by the Dimerization of Pd(0)-Complexed Alkenylcarbenes Generated from π-Allylpalladium Intermediates

Pd(0)-complexed 3-aryl or 2,3-diaryl propenylcarbenes generated from α-silyl-, α-germyl-, or α-boryl-σ-allylpalladium intermediates undergo self-dimerization to provide 1,6-di- or 1,2,5,6-tetraarylhexa-1,3,5-trienes in good to high yields. This method allows the use of a π-allylpalladium intermediate for a carbenoid precursor. Furthermore, the obtained 1,2,5,6-tetraarylhexa-1,3,5-trienes exhibit aggregation-induced emission enhancement property.