A straightforward route to obtain 13C1-labeled clenbuterol

Singly-labeled 13C1-clenbuterol has been synthesized employing a straightforward pathway starting from easily available acetanilide. The critical step was the Friedel–Crafts acylation of this compound with marked acetyl chloride, being the first example of the use of this methodology applied to the synthesis of a clenbuterol derivative. Subsequent chemical reactions afforded the desired product with good yields.