Saizo Shibata

Two new coumarins in Boenninghausenia albiflora

Abstract Two new isomeric coumarins were isolated from leaves of Boenninghausenia albiflora Reichb. Their structures were elucidated as (E)-7-hydroxy-6-(3-hydroxy-3-methyl-1-butenyl)-2(H)-1-benzpyran-2-one and (Z)-7-hydorxy-6-(3-hydroxy-3-methyl-1-butenyl)-2(H)-1-benzopyran-2-one.

Novel low molecular renin inhibitors which show good oral blood pressure lowering effects in marmosets

A series of low molecular renin inhibitors (molecular weight ∗< 600) were prepared and their biological activities were evaluated. The inhibitors containing indole-2-carbonyl moieties at the P3 position and 2-amino-3,5-anti-diol fragment at the P1-P1′ position showed renin inhibitory activities with IC50 of 10−8 M order and good blood pressure lowering effects after oral administration to sodium-depleted marmosets.

Diastereoselective aldol reaction of an α-alkoxycarbonylamino aldehyde with a silyl enol ether

Abstract The aldol reaction of optically active α-alkoxycarbonylamino aldehydes with a silyl enol ether in the presence of a Lewis acid afforded γ-amino-β-hydroxyketones diastereoselectively. The effect of the α-amide proton on the diastereoselectivity is discussed.