- One-pot multistep mechanochemical synthesis of fluorinated pyrazolones
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Solventless mechanochemical synthesis represents a technique with improved sustainability metrics compared to solvent-based processes. Herein, we describe a methodical process to run one solventless reaction directly into another through multistep mechanochemistry, effectively amplifying the solvent savings. The approach has to consider the solid form of the materials and compatibility of any auxiliary used. This has culminated in the development of a two-step, one-jar protocol for heterocycle formation and subsequent fluorination that has been successfully applied across a range of substrates, resulting in 12 difluorinated pyrazolones in moderate to excellent yields.
- Howard, Joseph L.,Nicholson, William,Sagatov, Yerbol,Browne, Duncan L.
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p. 1950 - 1956
(2017/09/27)
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- N-Fluoro-bis[(trifluoromethyl)sulfonyl]imide: Interesting reactions involving nucleophilic attack on sulfonyl groups
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N-Fluoro-bis[(trifluoromethyl)sulfonyl]imide (1) undergoes reaction with a variety of nucleophiles to give a number of interesting products. Under suitable conditions, the sulfonyl group on 1 is subject to nucleophilic attack forming N-fluoro-trifluoromethylsulfonyl amide (3) and Nu-SO2CF3. Surprisingly, 3 can also function as a weak nucleophile in the absence of other stronger bases.
- Ying, Weiwen,Desmarteau, Darryl D.,Xu, Ze-Qi,Witz, Michael
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p. 135 - 139
(2007/10/03)
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- Selective, Electrophilic Fluorinations Using N-Fluoro-o-benzenedisulfonimide
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The synthesis of N-fluoro-o-benzenedisulfonimide (NFOBS, 2) and its use as an "electrophilic" fluorinating reagent with nucleophilic substrates is described and compared with that of N-fluorobenzenesulfonimide (NFSi, 3).NFOBS (2) is prepared in three steps in 81percent overall yield from commercially available o-benzenedisulfonic acid (4) and involves treatment of o-benzenedisulfonimide (6) with dilute fluorine (10percent F2/N2).Reaction of 2 with metal enolates, silyl enol ethers, and 1,3-dicarbonyl compounds affords the corresponding α-fluoro compounds in yields up to 95percent, with good control of mono- and difluorination.Fluorination of ortho-metalated aromatic compounds was achieved in modest to good yields (10-80percent).While the reactivities of 2 and 3 are similar, better yields were observed with the former reagent in the fluorination of metal enolates, Grignard and lithium reagents, while 3 gave better results with the ortho-lithiated aromatic substrates.The available evidence suggests an SN2-type mechanism for the fluorination of nucleophilic substrates by these reagents.
- Davis, Franklin A.,Han, Wei,Murphy, Christopher K.
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p. 4730 - 4737
(2007/10/02)
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