In the case of fluoromethyl derivatives cis-1b and cis-2b, the alternative synthetic scheme started with selective reduction of monoester 5 to alcohol 14 using the method mentioned above in 96% yield (Scheme 4). As expected, direct deoxofluorination of 14 was also unsuccessful, likely due to the competing elimination process. To overcome this issue, we temporarily masked the ester functionality in the molecule of 14. Thus, benzoylation of the hydroxyl moiety followed by selective cleavage of tert-butyl ester (that's why we could not use cis-4 as the starting material) gave carboxylic acid 15. A key precursor for the monofluorinationalcohol 16 was obtained after reduction of the COOH moiety with BH3•Me2S in 79% yield. Activation of the hydroxyl group with Tf2O and subsequent substitution with fluorine anion under mild conditions produced desired CH2F-substituted cyclobutane 17 in relatively low 11% yield. Unfortunately, elimination and other side processes remained a significant problem in this case. Nevertheless, cleavage of the ester moiety in the molecule of 17 with aqueous methylamine produced target alcohol 18 in 77% yield. Catalytic oxidation of the latter compound with RuCl3 -NaIO4 produced carboxylic acid cis-2b in 74% yield. Finally, modified Curtius rearrangement gave amine hydrochloride cis-1b in 71% yield. Despite the modest efficiency of the deoxyfluorination step, both building blocks were successfully obtained on a gram scale. Scheme 4. Synthesis of CH2F-substituted building blocks cis-1b and cis-2b.