Tomoaki Hamada

Zn-catalyzed asymmetric allylation for the synthesis of optically active allylglycine derivatives. Regio- and stereoselective formal alpha-addition of allylboronates to hydrazono esters.

We have developed Zn-catalyzed asymmetric allylation of hydrazono esters with allylboronates. The reactions proceeded smoothly in high yields and high stereoselectivities. Remarkably, formal α-addition occurred for α-substituted allylboronates exclusively, and excellent stereoselectivities were observed. This is the first example of catalytic regio- and stereoselective allylations with formal α-addition. In addition, the reaction proceeded in aqueous media, and the use of water is essential. Zn(OH)2 might be a catalyst in this asymmetric allylation, and the catalytic activity of Zn(OH)2 was confirmed. This is also the first case of chiral metal hydroxide-catalyzed asymmetric reactions.

Allylation reactions of carbonyl compounds using an organosilicon reagent in aqueous media

Allylation reactions of carbonyl compounds such as aldehydes and reactive ketones using allyltrimethoxysilane in aqueous media proceeded smoothly in the presence of 5 mol% of a CdF2-terpyridine complex; the presence of the ligand plays an important role for the catalytic activity; the catalyst was easily recovered and reused without loss of activity.