Scalable, Catalytic Asymmetric Synthesis of Syn, Anti Stereotriad Building Blocks for Polypropionate Antibiotics

A relay ring-closing metathesis synthesis of dihydrooxasilines, precursors of (Z)-iodo olefins

A convenient Grubbs II metathesis provides dihydrooxasilines by relay RCM (RRCM). Dihydrooxasilines undergo ring opening to give Z-vinyl silanes. These can then be converted to Z-vinyl iodides. This sequence provides a short, high yield, and convenient route to trisubstituted Z-vinyl iodides, useful intermediates for the preparation of polypropionate antibiotics.

Short synthesis of the C1-C14 stretch of discodermolide from building blocks prepared by asymmetric catalysis

A convergent and stereoselective synthesis of the C1-C14 stretch of (+)-discodermolide demonstrates the utility of the "asymmetric catalysis approach" to complex polypropionates. The preparation of this complex synthon requires 15 steps in the longest linear sequence and 19 steps total from inexpensive materials.

Deconstruction-reconstruction strategy for accessing valuable polyketides. Preparation of the C15-C24 stereopentad of discodermolide

An advanced, known intermediate for discodermolide synthesis was prepared by an efficient sequence from the readily available fermentation product oleandomycin. The scheme makes use of a new method for the direct cleavage of aminoglycosides, a critical double-bond isomerization, and a selective protection of two of three hydroxyl groups in a modified oleandolide. This synthesis illustrates a new strategy, "deconstruction-reconstruction", for accessing stereochemically complex polyketide building blocks.