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 C-43 hydroxyl group onto a C-38-C-39 epoxide. The C-38-C-39 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. (C) 2000 Elsevier Science Ltd. All rights reserved.