Selective, Electrophilic Fluorinations Using N-Fluoro-o-benzenedisulfonimide
摘要:
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 81% overall yield from commercially available o-benzenedisulfonic acid (4) and involves treatment of o-benzenedisulfonimide (6) with dilute fluorine (10% F-2/N-2). Reaction of 2 with metal enolates, silyl enol ethers, and 1,3-dicarbonyl compounds affords the corresponding alpha-fluoro compounds in yields up to 95%, with good control of mono- and difluorination. Fluorination of ortho-metalated aromatic compounds was achieved in modest to good yields (10-80%). 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 S(N)2-type mechanism for the fluorination of nucleophilic substrates by these reagents.
Selective, Electrophilic Fluorinations Using N-Fluoro-o-benzenedisulfonimide
摘要:
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 81% overall yield from commercially available o-benzenedisulfonic acid (4) and involves treatment of o-benzenedisulfonimide (6) with dilute fluorine (10% F-2/N-2). Reaction of 2 with metal enolates, silyl enol ethers, and 1,3-dicarbonyl compounds affords the corresponding alpha-fluoro compounds in yields up to 95%, with good control of mono- and difluorination. Fluorination of ortho-metalated aromatic compounds was achieved in modest to good yields (10-80%). 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 S(N)2-type mechanism for the fluorination of nucleophilic substrates by these reagents.
Snieckus Victor, Beaulieu Francis, Mohri Kunihiko, Han Wei, Murphy Christ+, Tetrahedron Lett, 35 (1994) N 21, S 3465- 3468
作者:Snieckus Victor, Beaulieu Francis, Mohri Kunihiko, Han Wei, Murphy Christ+
DOI:——
日期:——
Selective, Electrophilic Fluorinations Using N-Fluoro-o-benzenedisulfonimide
作者:Franklin A. Davis、Wei Han、Christopher K. Murphy
DOI:10.1021/jo00120a014
日期:1995.7
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 81% overall yield from commercially available o-benzenedisulfonic acid (4) and involves treatment of o-benzenedisulfonimide (6) with dilute fluorine (10% F-2/N-2). Reaction of 2 with metal enolates, silyl enol ethers, and 1,3-dicarbonyl compounds affords the corresponding alpha-fluoro compounds in yields up to 95%, with good control of mono- and difluorination. Fluorination of ortho-metalated aromatic compounds was achieved in modest to good yields (10-80%). 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 S(N)2-type mechanism for the fluorination of nucleophilic substrates by these reagents.
N-fluoro-o-benzenedisulfonimide: a useful new fluorinating reagent
作者:Franklin A. Davis、Wei Han
DOI:10.1016/s0040-4039(00)74290-0
日期:1991.3
N-Fluoro-o-benzenedisulfonimide (5) is a stable, easily prepared, highly efficient source of “electrophilic” fluorine which fluorinates enolates, azaenolates and carbanions in good to excellent yields.