Total Synthesis and Biological Evaluation of 19-Hydroxysarmentogenin-3 -O-α-l-rhamnoside, Trewianin, and Their Aglycons.

Cardenolides comprise an important family of natural steroids with a wide spectrum of biological activities. Although 19-hydroxysarmentogenin-3- O-α-l-rhamnoside (1a) and trewianin (1b) were structurally determined to have cardenolide structures, their biological activities have not been evaluated. The 6/6/6/5-membered ABCD-ring systems of both 1a and 1b are decorated by a β-oriented C17-butenolide, three C11,14,19-hydroxy groups, and a C3-O-l-rhamnoside moiety.

Designer μ-oxo-bridged hypervalent iodine(III) organocatalysts for greener oxidations.

The in situ generated μ-oxo-bridged reactive hypervalent iodine(iii) species 1 or their analogues are introduced as more efficient organocatalysts for the catalytic strategy for realizing practical and greener oxidations.