Next, fatty acids were selectively introduced to determine which hydroxy groups were least reactive, as well as to investigate the gelation property of a compound in which three of the four hydroxy groups of 1,5-GL have fatty acids and one is a free hydroxy group. We attempted to selectively introduce fatty acids by closely monitoring the reaction with thin-layer chromatography (TLC) and terminating it midway. The fatty acid introduced here was palmitic acid, and the reaction conditions were the same as for the synthesis of C16GL (4) except for the reaction time (Scheme 2). In a mixture crystallized in acetone, the main compound with a lower Rf value on TLC than fully palmitoylated C16GL (4) was purified using silica gel column chromatography, crystallized, and the structure was confirmed using NMR. H-1 H COSY NMR showed that the hydroxy group at position 5 was free ( 4.11 (H-5) → 2.75 (OH)), and HMBC-NMR showed that it was a five-membered ring cyclized at 1,4 ( 4.70 (H-4) → 169.19 (C-1)). Compound 7 (5-OH-C16GL) was confirmed with a free hydroxy group at position 5. This revealed that the hydroxy group at position 5 was the least reactive of the 1,4-GL hydroxy groups.