Anti-depressive activities and biotransformation of timosaponin B-III and its derivatives.

Timosaponin B-III (TB-III) is a steroidal saponin isolated from the rhizome of Anemarrhenae asphodeloides (Liliaceae). The biotransformation of TB-III by β-glucosidase was investigated. Three biotransformation products were isolated and their structures were identified as timosaponin B-III-a (M1), (20R,25S)-5β-spirostane-3β-ol-3-O-β-D-glucopyranosyl-(1 → 2)-β-D-galacopyanoside (M2) and timosaponin AIII (M3).

Bifunctional homoallylic carbamates from chiral silane additions to in situ generated N-acyl iminium ions.

Homoallylic carbamates bearing an α,β-unsaturated ester or an allylic carbonate were generated respectively utilizing novel chiral silanes through Lewis acid promoted asymmetric aminocrotylation. Those bifunctional building blocks could further undergo Michael addition or cyclization to selectively form functionalized lactams, azetidines, and tetrahydropyrimidinones.