Lactam analogues of galiellalactone

A synthetic route to lactam analogues of the fungal STAT3 inhibitor galiellalactone is presented. The synthesis involves a one-pot tosylamide amide coupling/intramolecular Michael addition and an introduction of an α,β-unsaturation, regioselectively directed by the tosyl functionality. An iodolactonization of the octahydroindolizine 9 and a re-opening of the lactone were employed for introducing an iodo substituent, facilitating the preparation of 8-substituted analogues (e.g., 4) using a Suzuki cross-coupling.

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