“…Because the preparation of yohimbic acid esters by the above-described synthetic route using alcohols with the hydroxy group attached directly to a four-membered cycle proved to be problematic, a different synthetic approach was needed. N -Boc-protected amino alcohols were converted into alkylating agents using mesyl chloride and subsequently treated with the cesium salt of yohimbic acid ( 2 , Scheme ) according to described procedures. , Removal of protecting groups and reaction workup were performed in the same way as above. This approach afforded good yields of target compounds 4m – 4q (Scheme ), and their purification was also found to be easier.…”