Oxathiolane, fluorination

Hydroxypiperidine alkaloids have been synthesized via anodic methoxylation that allowed the regio- and stereoselective introduction of substituents [213]. A highly diastereoselective fluorination was achieved with chiral l,3-oxathiolan-5-ones derived from camphorsulfonamide. In dimethoxyethane containing Et4NF-4HF, the monofluorinated product (9) was obtained as a single diastereomer [214]. 

It has been shown that it is possible to exchange one halogen for another at the 4-position of a l,3-oxathiolan-5-one (Equation 20), as chlorine is efficiently replaced by fluorine using HF in the presence of triethylamine and zinc bromide <2002SL996>. 

Oxathiolanes, 1,2-Dithiolanes, 1,3-Dithiolanes, and 1,2,3-Trithio-lanes Only three types of fluorinated 1,3-oxathiolanes derivatives are known ... 

In Et4NF -4HF 2-substituted l,3-dithiolan-4-ones are converted into mono-fluoro derivatives (98EA(43)1985). Table 5 presents data on anodic fluorination of 2-sub-stituted l,3-oxathiolan-5-ones, forming monofluoro derivatives 10 (03JFC(121)93, 99JOC133). The fluoride ion plays a very important role in this process. As can be seen from Table 5, the Et3N 3HF system is unsuitable for anodic fluorination of the... 

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