Abstract
Attempts to obtain an unsaturated macrocycle (3) using the Wittig reaction of furan-2, 5-bis (methylenetriphenyl phosphonium chloride) (1) with 2, 5-furan-bis (2-cis-4-trans-2, 4-dimethyl-2, 4-pentadienal) (2) were unsuccessful by the occurence of undesired 1, 6-elimination of triphenylphosphine from bisphosphonium salt (1). In an alternative reaction of 2, 5-furandialdehyde with furan-2, 5-bis (2-cis-4-trans-2, 4-dimethyl-2, 4-pentadienyl triphenyl phosphonium bromide) gave major formation of uncyclized polyendial isomers, and no unsaturated macrocycle (3) was isolated. Three isomers of polyendials of 17, 18 and 19 were purely isolated and assigned their structures.
