127184-04-7Relevant articles and documents
Asymmetric Fluorination of Enolates with Nonracemic N-Fluoro-2,10-Camphorsultams
Davis, Franklin A.,Zhou, Ping,Murphy, Christopher K.,Sundarababu, Gajendran,Qi, Hongyan,Han, Wei,Przeslawski, Robert M.,Chen, Bang-Chi,Carroll, Patrick J.
, p. 2273 - 2280 (1998)
The asymmetric "electrophilic" fluorination of tertiary enolates by nonracemic N-fluoro-2,10-camphorsultams 3 affords quaternary α-fluoro carbonyl compounds in modest yield and ee. The highest asymmetric induction was observed for the fluorination of the sodium enolate of 2-methyl-1-tetralone (8a) by (-)-N-fluoro-2,10-(3,3-dichlorocamphorsultam) (3b) to give (S)-(+)-2-fluoro-2-methyl-1-tetralone (9a) in 70percent ee. The absolute configuration was established by X-ray crystallography of the corresponding diastereomeric β-hydroxy sulfoximine prepared from (±)-9a and the Johnson reagent. The asymmetric induction exhibited by 3 is opposite to that of the closely related enolate hydroxylation reagents nonracemic (camphorylsulfonyl)oxaziridines 4. The N-fluoro sultams 3 were prepared by fluorination (10percent F2/N2) of the corresponding sultams 5.
Enantioselective Synthesis of Tertiary α-Hydroxy Carbonyl Compounds Using ((8,8-Dichlorocamphoryl)sulfonyl)oxaziridine
Davis, Franklin A.,Weismiller, Michael C.
, p. 3715 - 3717 (1990)
Very high stereoinduction, generally 90-95percent ee, is observed for the asymmetric oxidation of 2-substituted-1-tetralone enolates to 2-hydroxy-2-substituted-1-tetralones by chiral nonracemic oxaziridine (+)-7.Not only are these α-hydroxy carbonyl compounds difficult to prepare enantiomerically pure via other methods, but they are also models for several biologically active compounds.
Chemistry of Oxaziridines. 18. Synthesis and Enantioselective Oxidations of the oxaziridines
Davis, Franklin A.,Weismiller, Michael C.,Murphy, Christopher K.,Reddy, R. Thimma,Chen, Band-Chi
, p. 7274 - 7285 (2007/10/02)
The synthesis and enantioselective oxidations of oxaziridines 13 are reported.These reagents are prepared in two steps from the (camphorylsulfonyl)imine 4 by treatment of the corresponding azaenolate with electrophilic halogen sources followed by biphasic oxidation of the resulting dihalo imine 6-9 with m-CPBA/K2CO3.Of these oxaziridines the dichloro reagent 13b, available on a multigram scale, affords the highest enantioselectivities for the asymmetric oxidation of sulfides to sulfoxides (42-74 percent) and for the hydroxylation of enolates (often better than 95 percent ee).In general the molecular recognition is predicted and explained in terms of minimization of nonbonded steric interactions in the transition states.For the asymmetric oxidation of sulfides to sulfoxides, secondary electronic factors related to the polarity of the sulfide and oxaziridine also play a role.Definitive evidence for chelation of the metal enolate with the C-X bond in 13 is not found.The molecular recognition is interpreted in terms of the higher reactivity of the reagents and an active-site structure which is sterically complementary with the enolate.For the asymmetric hydroxylation of the Z- and E-enolates of propiophenone (16a), the Z-enolate exhibits much higher stereoselectivity than the E-enolate: >95 percent vs 22 percent ee.
A convenient, improved synthesis of (camphoryl)sulfonyl oxaziridines
Mergelsberg,Gala,Scherer,DiBenedetto,Tanner
, p. 161 - 164 (2007/10/02)
A convenient, efficient procedure for the large scale synthesis of chiral oxidizing reagents (+), and (-)-((8,8-dichlorocamphory)sulfonyl)oxaziridine, 5, as well as of 8,8 unsubstituted (+), and (-) (camphoryl)sulfonyl oxaziridine, 4, from (+), or (-) (camphoryl)imine, 2, in step yields of 83% to 95%, is reported.
