Ryohei Nagase

Ti-direct, powerful, stereoselective aldol-type additions of esters and thioesters to carbonyl compounds: application to the synthesis and evaluation of lactone analogs of jasmone perfumes

An efficient TiCl(4)-Et(3)N or Bu(3)N-promoted aldol-type addition of phenyl and thiophenyl esters or thioaryl esters with aldehydes and ketones was performed (total 46 examples). The present method is advantageous from atom-economical and cost-effective viewpoints; good to excellent yields, moderate to good syn-selectivity, substrate variations, reagent availability, and simple procedures. Utilizing the present reaction as the key step, an efficient short synthesis of three lactone [2(5H)-furanone] analogs of jasmine perfumes was performed. Among them, the lactone analog of cis-jasmone had a unique perfume property (tabac).

Ti-mediated direct and highly stereoselective Mannich reactions between esters and oximeethers

The first general method of direct and highly stereoselective Ti-mediated Mannich reaction between three types of simpleesters and E and Z mixtures of oxime ethers (aliphatic and aromatic) is accomplished.