“…Halogenated nucleosides represent an important class of synthetic drugs used in anticancer and antiviral treatments, including Cladribine ( 1 , anti‐leukaemia), Clofarabine ( 2 , anti‐leukaemia), Fludaradine ( 3 , anti‐leukaemia), Fluorouracil ( 4 , antitumor), Gemcitabine ( 5 , anticancer), and Sofosbuvir ( 6 , anti‐Hepatitis C; Figure A). In contrast, there are relatively few known halogenated nucleoside natural products, with nucleocidin ( 7 a , fluorinated at C4′ of ribose), AT‐265 ( 7 b , dealanylascamycin, chlorinated at C2 of adenosine), and adechlorin ( 8 , chlorinated at C2′ of ribose; Figure B) being rare examples. Adechlorin is the 2′‐chloro derivative of pentostatin ( 9 ), a competitive inhibitor of adenosine deaminase that is approved as a drug for leukaemia treatment .…”