Design, synthesis, and evaluation of biotinylated opioid derivatives as novel probes to study opioid pharmacology.

A generally applicable strategy of chemically labeling (-)-morphine (1) is described. The synthesis starts from commercially available starting materials and can be completed in two steps with an overall yield of 23%. In silico simulation and NMR results show that the binding of (-)-morphine to one of its molecular targets, toll-like receptor 4 (TLR4), was not affected by the modification.