An approach toward the total synthesis of subergorgic acid

Ireland–Claisen rearrangement of a substituted alkenyl cyclopentanecarboxylate provided a monocyclic isomer containing the proper stereochemistry for four of the five stereogenic centers in subergorgic acid. Efforts to construct the additional rings in the molecule were thwarted as a result of steric and other factors. The results provide insights regarding the Ireland–Claisen rearrangement in five-membered ring systems. The formation of spiro-compounds from sterically and stereoelectronically demanding systems as reported herein has the potential to serve as a general strategy for the synthesis of such sub-units in both natural and unnatural products.