Rheosmin (?Raspberry Ketone?) and Zingerone, and Their Preparation by Crossed Aldol-Catalytic Hydrogenation Sequences

Preparations of the two closely-related natural products rheosmin (“raspberry ketone”, 4-(4′-hydroxyphenyl)-2-butanone) and zingerone (4-(4′-hydroxy-3′-methoxyphenyl)-2-butanone), are well-suited for the introductory organic laboratory. The crossed-aldol condensation of 4-hydroxybenzaldehyde with acetone gives an adduct (4-(4′-hydroxyphenyl)-3-buten-2-one), which is hydrogenated cleanly over rhodium on alumina to form rheosmin. Condensation of...