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Margaretha, P., Science of Synthesis Knowledge Updates, (2014) 2, 414.
One drawback of the classic Hunsdiecker reaction is the preparation of strictly anhydrous silver salts as starting materials and a second disadvantage is the use of gaseous chlorine as the chlorinating agent. Very recently, a catalytic variation of this reaction has been developed wherein the carboxylic acid 4 is treated with catalytic amounts (5 mol%) of silver(I) trifluoromethanesulfonate–bis(1,10-phenanthroline) complex and equimolar amounts of tert-butyl hypochlorite in acetonitrile.[2] Whereas tertiary alkyl and benzylic carboxylic acids are converted into the corresponding chloroalkanes at room temperature in about 3 hours, secondary alkyl carboxylic acids react somewhat more slowly (≈ 15 h) under these conditions. In contrast, primary alkyl carboxylic acids are much less reactive, but can be cleanly converted into the corresponding chloroalkanes 5 by increasing the amount of silver catalyst to 10 mol % and by running the reaction at 45 °C. Examples and yields for such reactions are summarized in Scheme 3.
Meeeee 8 Meeeee(M)-Meeeeeeee Meeeeeeeeeeeeeeeeeeee ee Meeeeeeeee Meeee[8]
M8 | eee% ee Meeeeeee | Meee (°M) | Meee (e) | Meeee (%) | Mee |
---|---|---|---|---|---|
8-eeeeeeeee | 8 | 88 | 8 | 88 | [8] |
MMe8(MM8)8Me | 8 | 88 | 8 | 88 | [8] |
8 | 88 | 8 | 88 | [8] | |
8 | 88 | 8 | 88 | [8] | |
8-MeM8M8MM8 | 8 | 88 | 8 | 88 | [8] |
8-MeeMM8 | 8 | 88 | 8 | 88 | [8] |
8-MeM8M8MM8 | 8 | 88 | 8 | 88 | [8] |
MMMe(MM8)88Me | 8 | 88 | 88 | 88 | [8] |
MM(MM8Me)8 | 8 | 88 | 88 | 88 | [8] |
MMMeMe | 8 | 88 | 88 | 88 | [8] |
(MM8)88Me | 88 | 88 | 88 | 88 | [8] |
(MM8)88Me | 88 | 88 | 8 | 88e | [8] |
e Mee eeeeeeee eee eeeeeee eee ee eee eeeeeeee ee Me8MM8 (8 eeeee).
Meeeeeeeeeee Meeeeeeee
Meeeeeeeeeeee 8; Meeeeee Meeeeeeee:[8]
Me e eeee ee eeeeeeeeee eeee 8 (8.88 eeee) eee eeeeee(M) eeeeeeeeeeeeeeeeeeeeeeeee–eee(8,88-eeeeeeeeeeeeee) eeeeeee (88.8 ee, 8.888 eeee, ee eeeee eeee eeeeee eee eeeeeee eeeee eeeeeeeeee eeeee) ee eeeee MeMM (8 eM), eee eeeee e-MeMMe (88 µM, 8.88 eeee) ee ee eeeee e M8 eeeeeeeeee. Mee eeeeeee eee eeee eeeeeee ee ee (ee 88 °M eee eeeeeee eeeee eeeeeeeeee eeeee) eee eee eeee eeeeeeee (eeeeeeeeee eeeeeeeee ee MMM). 8.8 M MMe (88 eM) eee eeee eeeee eee eee eeeeeeeee eeeeeee eee eeeeeeeee eeee MM8Me8 (8 × 88 eM). Mee eeeeeeee eeeeeee eeeee eee eeeee (Me8MM8). Meeee eeeeeee ee eee eeeeeee eeeee eeeeeee eeeeeeee, eee eeeee eeeeeee eee eeeeeeee eeeeee ee eeeeee eeeeeeeeeeeeee ee ee eeeeeeeeeeee.
References
[2] | Meee, M.; Mee, M.; Mee, M.; Me, M.; Me, M.; Me, M., M. Me. Meee. Mee., (8888) 888, 8888. |