FR901464:  Total Synthesis, Proof of Structure, and Evaluation of Synthetic Analogues

The natural product FR901464 (1) was isolated by the Fujisawa Pharmaceutical Co. and shown to have intriguing biological properties including impressive antitumor activity. In this paper we describe the first total synthesis of 1 in full detail. A chiral building block synthetic strategy was used to assemble the target: optically active components were generated using asymmetric catalytic reactions, and these fragments were coupled together at a late stage in a convergent synthesis. In particular, a versatile, asymmetric hetero-Diels−Alder (HDA) reaction was developed in the context of this synthesis and used with great effectiveness for the preparation of the two densely functionalized pyran rings. The flexible nature of the synthetic route also allowed us to prepare a series of analogues of 1. These compounds were used to prove the relative stereochemistry of the natural product as well as to probe the importance of certain structural features of FR901464 with regard to biological activity.