222312-03-0Relevant articles and documents
The formation of halogenated succinates by liquid-phase direct fluorination with elemental fluorine
Syvret, Robert G.,Vassilaros, Daniel L.,Parees, David M.,Pez, Guido P.
, p. 277 - 282 (2007/10/02)
Direct fluorination of maleic anhydride with elemental fluorine has been investigated in different solvents at low temperatures.It was discovered that the net conversion of maleic anhydride, as well as the overall yield and composition of the halogenated products, depend strongly on the experimental conditions employed.Fluorinations conducted in fluorotrichloromethane, chloroform or mixtures thereof, in the presence of sodium fluoride, resulted in good yields of halogenated succinic acid derivatives: the predominant products being 2,3-dihalogenated succinic acids.Product distributions varied widely between experiments conducted at 0 deg C and -25 deg C, and also between experiments conducted in neat CHCl3 and in CFCl3/CHCl3 mixtures.Experimental details and some comments regarding the stereoselectivity of halogen addition are provided.
STEREOCHEMISTRY OF α,α'-DIFLUOROSUCCINIC ACIDS
Bell, H. M.,Hudlicky, M.
, p. 191 - 200 (2007/10/02)
Treatment of both dimethyl (-)-D-tartrate (IVa) and dimethyl (+)-L-tartrate (Va) with sulfur tetrafluoride gave dimethyl meso-α,α'-difluorosuccinate (Ia).The same reagent converted dimethyl meso-tartrate (IIIa) to a racemic mixture of dimethyl D- and L-α,α'-difluorosuccinate (IIa).This outcome resulting from the replacement of hydroxyl by fluorine with inversion of configuration at one and retention of configuration at the other chiral carbon atom can be rationalized by assuming the formation of a cyclic intermediate.This is opened by a subsequent SN2 reaction with fluoride ion followed by a four-center displacement of sulfuroxy group by fluorine.The respective configuration of the dimethyl α,α'-difluorosuccinates Ia and IIa were established by (1)H and (19)F NMR using an optically active chemical shift reagent and confirmed by converting the esters to the corresponding acids and these in turn to the cis- and trans-α,α'-difluorosuccinic anhydrides, respectively.
