Multiple Enone-Directed Reactivity Modes Lead to the Selective Photochemical Fluorination of Polycyclic Terpenoid Derivatives.
In the realm of aliphatic fluorination, the problem of reactivity has been very successfully addressed in recent years. In contrast, the associated problem of selectivity, that is, directing fluorination to specific sites in complex molecules, remains a great, fundamental challenge. In this report, we show that the enone functional group, upon photoexcitation, provides a solution. Based solely on orientation of the oxygen atom, site-selective photochemical fluorination is achieved on steroids and bioactive polycycles with up to 65 different sp3C-H bonds. We have also found that γ-, β-, homoallylic, and allylic fluorination are all possible and predictable through the theoretical modes reported herein. Lastly, we present a preliminary mechanistic hypothesis characterized by intramolecular hydrogen atom transfer, radical fluorination, and ultimate restoration of the enone. In all, these results provide a leap forward in the design of selective fluorination of complex substrates that should be relevant to drug discovery, where fluorine plays a prominent role.
Department of Chemistry, Johns Hopkins University , 3400 N. Charles Street, Baltimore, Maryland 21218, United States.
Cody Ross
0000-0003-1047-8924
CR
Pitts
Department of Chemistry, Johns Hopkins University , 3400 N. Charles Street, Baltimore, Maryland 21218, United States.
Desta Doro
DD
Bume
Department of Chemistry, Johns Hopkins University , 3400 N. Charles Street, Baltimore, Maryland 21218, United States.
Stefan Andrew
SA
Harry
Department of Chemistry, Johns Hopkins University , 3400 N. Charles Street, Baltimore, Maryland 21218, United States.
Maxime A
MA
Siegler
Department of Chemistry, Johns Hopkins University , 3400 N. Charles Street, Baltimore, Maryland 21218, United States.
Thomas
T
Lectka
D054879:Halogenation; D006845:Hydrocarbons, Fluorinated / Q000138:chemical synthesis* / Q000737:chemistry; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D055668:Photochemical Processes; D011083:Polycyclic Compounds / Q000737:chemistry*; D013729:Terpenes / Q000737:chemistry*
D006845:Hydrocarbons, Fluorinated; D007659:Ketones; D011083:Polycyclic Compounds; D013729:Terpenes