A better understanding of the reaction mechanism might pave the way for future experiments to shift the product distribution towards the C(11)-isomer. As discussed, initial proposals on the acid-mediated reactivity of Fdx towards nucleophiles suggested an SN2''-mechanism. As in this work, three regioisomers C(11), C(13) and C(15) were obtained, the reaction does not proceed via a SN2'' mechanism solely. Further, retention of configuration was observed for the C(11)-isomer. Thus, a direct SN2-type mechanism can be ruled out. To exclude that the formal SN2'' product, rearranges to the other regioisomers, the isolated C(15)-isomer was resubjected to the reaction conditions in absence of a thiol. On the reaction time scale no conversion of the