Synergistic silver/scandium catalytic spiroketalization of β-alkynyl ketones for the atom economical synthesis of skeletally diverse spirocyclic isochromenes

Two types of new synergistic silver/scandium catalytic spiroketalizations of β-alkynyl ketones have been achieved, delivering a variety of skeletally diverse spirocyclic isochromenes in generally good yields.

Benzannulated spiroketal natural products: isolation, biological activity, biosynthesis, and total synthesis

A review discussing the isolation, biological activity, biosynthesis, and total synthesis of naturally occurring benzannulated spiroketals.

Synergistic silver/scandium catalysis for divergent synthesis of skeletally diverse chromene derivatives

The combination of AgTFA and Sc(OTf)₃ enables the bimetallic synergistic catalysis of β-alkynyl ketones and o-hydroxybenzyl alcohols, allowing divergent synthesis of three classes of skeletally diverse chromene derivatives with generally high diastereoselectivity through dehydroxylated bi- and tri-cyclization cascades.

Synthesis and X-Ray Crystal Structure of Cynandione B Analogues

The synthesis of analogues of cynandione B, a phenolic acetophenone from Cynanchum taiwanianum, is described. The one-step conversion of benzochromenones to the heptacyclic spiroacetal core of cynandione B using methylmagnesium bromide is investigated and structural requirements for this novel transformation established. X-ray crystal structure analysis has established the relative configuration in these unusual heterocycles.