Synthetic Strategies of Marine Polycyclic Ethers via Intramolecular Allylations:  Linear and Convergent Approaches

Abstract

Strategies for the synthesis of polycyclic ethers based on intramolecular allylations are overviewed. The intramolecular condensation of allylic stannanes and aldehydes is a powerful tool for the synthesis of oxepane derivatives. The reaction is successfully applied to the iterative total synthesis of hemibrevetoxin B (2). Further, the intramolecular allylation of alpha-acetoxy ethers provides an efficient method for the convergent synthesis of polycyclic ethers. The usefulness of the latter strategy is demonstrated in the convergent total synthesis of gambierol (4).

Enantiodifferentiation of Aliphatic Ethers by the Dirhodium Method

“…So, we selected three chiral ethers (as racemates) representing a wide range of typical ether structures, acyclic dialkyl ethers (3), tetrahydrofurans (4) and tetrahydropyrans (5). The NMR spectroscopic data obtained for those ligands are collected in Table 1 as well.…”

“…This encouraged us to subject another hard functionality to the dirhodium complex experiment, namely chiral aliphatic ethers (Scheme 2), a class of compounds which occurs quite frequently among [ natural products and is, therefore, an object of intensive synthetic effort. [5] There is no doubt that a safe and easy-toapply analytical method to determine enantiomeric ratios is urgently required. To the best of our knowledge, however, such a method for direct observation does apparently not exist.…”

Bioinspired iterative synthesis of polyketides

“…The iterative strategies have also been successfully used in the total synthesis of polycyclic ethers (Zakarian et al, 2003 ; Kadota and Yamamoto, 2005 ; Clark, 2006 ). Though there are still many problems for an ideal automation synthesis, purification constitutes one of the tough ones.…”

Strategies for the Synthesis of Cyclic Ethers of Marine Natural Products

“…Formal synthesis of (+)-muconin (2) As mentioned earlier, polycyclic ether natural products are formed by a cascade cyclization of a polyepoxide backbone. Therefore, epoxide-opening cascades have been used as a valuable method for synthesizing this type of compound.…”