analogue of the grapefruit odorant rhubafuran (1a), was synthesized and isolated as a 1:1 mixture of two racemic diastereomers. In addition, the structurally related racemic C/Si pairs 2a/2b and 3a/3b were prepared. To get information about structure–odor relationships in the domain of grapefruit odorants, the C/Si pairs 1a/1b, 2a/2b, and 3a/3b were studied for their olfactory properties.