Regioselective synthesis of bifunctional macrolides for probing ribosomal binding

[structure: see text] Bifunctional macrolides projecting an anchor group to the right or left spatial position of the lactone ring were synthesized. The regioselectivity of the key [3 + 2] cycloaddition process was controlled by the remote cladinose group attached to the C-3 position. These conformationally constrained molecules were employed as molecular probes to study the ribosomal binding sites of bifunctional macrolide antibiotics.