Targeted synthesis of macrodiolides containing bis-methylene-separated Z-double bonds and their antitumor activity in vitro

An original strategy has been developed for the synthesis of valuable unsaturated macrocyclic lactones, macrodiolides, containing a 1Z,5Z-diene moiety in 57–79% yields and >98% stereoselectivity by hafnium triflate Hf(OTf)₄-catalyzed intermolecular esterification of aliphatic α,ω-dicarboxylic acids with α,ω-alka-nZ,(n+4)Z-dienediols (1,12-dodeca-4Z,8Z-dienediol, 1,14-tetradeca-5Z,9Z-dienediol, 1,18-octadeca-7Z,11Z-dienediol). The diols were obtained by homo-cyclomagnesiation of tetrahydropyran ethers of oxygenated 1,2-dienes with EtMgBr in the presence of Mg metal and Cp₂TiCl₂ catalyst (10?mol. %). The resulting macrodiolides exhibit high cytotoxic activity in vitro against Jurkat, K562, U937, Hek293 and HeLa tumor cell lines.