Asymmetric Epoxide Cyclisation Route to the F-pyran Fragment of the Altohyrtins and Key Aldol Studies

The evolution of an asymmetric synthesis of a differentially protected F-pyran ring of the altohyrtins is described, which relies on a key intramolecular cyclisation of a C43 hydroxyl group onto a C38–C39 epoxide. The C38–C39 epoxide stereochemistry was achieved through optimisation of substrate control. Key aldol studies towards coupling the F-pyran ring with an E-pyran ring precursor was investigated, but unsuccessful.