Page 286 - Arrow Pushing in Inorganic Chemistry A Logical Approach to the Chemistry of the Main Group Elements

THE HALOGENS
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The following is a good example of such a reaction (LDA = lithium diisopropylamide):

O OLi
LDA

CH 3 CH 2
(7.38)
O
2 2
(CF 3 SO ) NF
F
CH 2
Interestingly, -diketones may be fluorinated without prior conversion to enolates:

H H F F
O O O O
(CF SO ) NF (7.39)
2 2
3
CH 3 CH 3 CH 3 CH 3

In addition, a number of steroidal silyl enol ethers and enol esters have been selectively
fluorinated by Selectfluor, as shown below:

OR O
Me Me
Me Me F
Selectfluor-(BF 4 ) 2
(a)
CH 3 CN, RT,
2 h (R = Ac)
AcO 15 min (R = SiMe 3 ) AcO
Silyl enol ether
derived from androsterone > 90%
AcO AcO
Me Me
Me Me
Selectfluor-(BF 4 ) 2
(b)
AcO O
F
Testosterone enol acetate > 95%
(7.40)
Finally, aromatics with electron-donating substituents may also be fluorinated by N-fluoro
reagents.