A pd‐Catalyzed Three‐Component Approach for the Synthesis of Monomeric and Dimeric Tetrahydro‐ 4H ‐Furo[2,3‐b]Chromene Steroids

The three‐component reaction of a steroid bearing a dihydrofuran ring, with methyl orthoformate and salicylaldehyde produced chromanketals through a [4 + 2] inverse electron demand cycloaddition. Substitution of salicylaldehyde by 2‐formylestradiol 17‐monoacetate afforded hybrid dimers having an androstane framework connected to an estrane nucleus through a tetrahydro‐4H‐furo[2,3‐b]chromene moiety. 1D and 2D NMR experiments provided enough evidence on the structure of the obtained compounds. X‐ray diffraction corroborates the proposed structures.