Structures of three disubstituted [13]-macrodilactones reveal effects of substitution on macrocycle conformation

The synthesis and crystal structures of three new disubstituted [13]-macrodilactones, namely, trans -4,8-dimethyl-1,10-dioxacyclotridec-5-ene-2,9-dione, C 13 H 20 O 4 , I , cis -4-(4-bromophenyl)-13-methyl-1,10-dioxacyclotridec-5-ene-2,9-dione C 18 H 21 BrO 4 , II , and trans -11-methyl-4-phenyl-1,10-dioxacyclotridec-5-ene-2,9-dione, C 18 H 22 O 4 , III , are reported and their conformations are put in the context of other [13]-macrodilactone structures reported previously. Together, they show that the number, location, and relative disposition of groups attached at the termini of planar units of the [13]-macrodilactones subtly influence their aspect ratios.