In this review, we examine the origins and synthesis of bioactive spiroketal-containing natural products isolated from traditional Chinese medicines.
Metal-free, electrochemical synthesis of spiroketals is presented, using anodic oxidation of malonic acids under mild conditions. This sustainable approach enables access to diverse spiroketal frameworks with potential for flow adaptation.
A CF3CO2H-catalyzed cycloaddition of o-hydroxy benzyl alcohols with isochroman ketals was reported, affording bisbenzannulated spiroketals and ether products concurrently and efficiently.
An Ir/Brønsted acid dual-catalyzed asymmetric cascade reaction of 2-(1-hydroxyallyl)phenols with isochroman ketals was developed, affording antifungal spiroketals with high enantioselectivities.
α-Keto ketals and benzannulated oxo-spiroketals have been regioselectively synthesized using a Sc3+-coordinated riboflavin tetraacetate photocatalyst with electron-deficient alkynes and alkynediols, respectively.