Hisashi Takei

Bio: Hisashi Takei is an academic researcher from Sumitomo Chemical. The author has contributed to research in topics: Sulfonium & Bromide. The author has an hindex of 9, co-authored 33 publications receiving 463 citations.

A Convenient Method for the Preparation of Ketones by the Reaction of Grignard Reagents with Carboxylic Acid Derivatives

Abstract: It was found that ketones were prepared in excellent yields by the reaction of Grignard reagents with S-(2-pyridyl) thioates and their analogues or with 2-pyridyl esters. The mechanism of this reac...

ADDITION REACTION OF THIOL TO OLEFIN BY THE USE OF TiCl4

Abstract: It was established that, in the presence of TiCl4, α,β-unsaturated carbonyl compounds react with ethanethiol at room temperature to afford the addition products, 3-ethylthiocarbonyl compounds, in good yields.

Toward a Synthetically Useful Stereoselective C−H Amination of Hydrocarbons

Abstract: Reaction between a sulfur(VI) compound and an iodine(III) oxidant in the presence of a catalytic quantity (≤3 mol %) of a rhodium(II) catalyst leads to the formation of a chiral metallanitrene of unprecedented reactivity. The latter allows intermolecular C−H amination to proceed in very high yields up to 92% and excellent diastereoselectivities up to 99% with C−H bond containing starting materials as the limiting component. The scope of this C−H functionalization includes benzylic and allylic substrates as well as alkanes. Secondary positions react preferentially, but insertion into activated primary C−H bonds or sterically accessible tertiary sites is also possible. Cooperative effects between the nitrene precursor and the chiral catalyst at the origin of these good results have also been applied to kinetic resolution of racemic sulfonimidamide. This methodology paves the way to the use of Csp3−H bonds as synthetic precursors for the introduction of a nitrogen functionality into selected positions.