Synthesis of polycyclic ethers

Stereocontrolled synthesis of polycyclic ethers and related heterocycles via intramolecular reactions of allylstannanes 97YGK619. 

An intramolecular acyl radical cyclization of acyl selenide 1024 uses a (Z)-vinylogous sulfonate to control rotamer population, affording ry -2,6-disubstituted tetrahydropyran-4-one 1025, a key intermediate during synthesis of the tetrahydropyran unit of mucocin (Equation 399) <1997TL5249>. This methodology is also applicable to the synthesis of polycyclic ethers <1996JOC4880>. 

The synthesis of polycyclic ethers with variable ring sizes can be conducted by two-directional double ring-closing metathesis. This methodology was used to prepare, in one-step, the tricyclic ether 73, which has a six-, seven-, and eight-membered ring (Scheme 9) <2000AGE372>. 

Kadota, I., Ohno, A., Matsuda, K., and Yamamoto, Y. 2002. Convergent synthesis of polycyclic ethers via the intramolecular allylation of alpha-acetoxy ethers and subsequent ring-closing metathesis. Journal of the American Chemical Society 124, 3562-3566. 

Sasaki, M., Fuwa, H. Total synthesis of polycyclic ether natural products based on Suzuki-Miyaura cross-coupling. Synlett 2004, 1851-1874. 

Yamamoto has investigated the intra-molecular condensation of y-(alkoxy)allylstaimanes with aldehydes as a general approach for the stereocontrolled synthesis of polycyclic ethers (Scheme 5.2.26). The strategy has been iteratively applied to the total synthesis of hemibrevetoxin B. i In this fashion, the Lewis acid-promoted reaction of 122 leads to formation of seven-membered ether 123, which is transformed into 124 for intra-molecular allylation to the fused-oxepane 125. 

Total synthesis of polycyclic ether ciguatoxin CTX3C 03YGK562, 04ACR961, 04SL577. 

Bartlett s research group has continued its work on the stereocontrol led synthesis of tetrahydrofurans and tetrahydropyrans, and has extended this work to the synthesis of polycyclic ethers as models for brevetoxin synthesis. Iodoetherification of the cyclohexanol (51) and subsequent rearrangement affords the tetrahydropyran (52), which in a subsequent iterative... 

The impressive molecular architecture and biological activities have made YTX and its analogs challenging synthetic targets. Efforts toward the synthesis of polycyclic ether frameworks of YTX and ATX have been reported mainly by Japanese groups. The obtained results represent a good prerequisite for the total synthesis of YTX that presumably will be accomplished in the near future. 

Sasaki, M. et al., A general method for convergent synthesis of polycyclic ethers based on Suzuki cross-coupling Concise synthesis of the ABCD ring system of ciguatoxin, Org. Lett., 1, 1075, 1999. 

Development and application of a convergent strategy for the total synthesis of polycyclic ether natural products 07BCJ856. 

As demonstrated throughout this review, rapid progress has been made in the field of the total synthesis of polycyclic ether natural products. Particularly, most of these accompUshments were concentrated over the last five years. Convergent assembly of the polycycUc ether fragments is, of course, the key to successful construction of the large ladder-shaped polycycUc ether system. In this context, the completed total syntheses have benefited enormously from the transition-metal catalyzed carbon-carbon bond forming reactions, such as olefin metathesis and cross-coupUng reactions. These powerful tools will imdoubtedly enable even more impressive accompUshments in this field. 

The size of the cavity in the crown ether can be tailored to allow for the selective binding of only certain cations—namely, those whose ionic radius is best accommodated by the polyether. This concept has been extended successfully into three dimensions by the synthesis of polycyclic ethers, also called cryptands (kryptos, Greek, hidden), which are highly selective in alkali and other metal binding (Figure 9-4). The significance of these... 

Cyclic oxonium ylides building blocks for iterative synthesis of polycyclic ethers. Marmsater, F.P., Vanecko, J.A., West, F.G. (2002), Tetrahedron, 58, 2027-2040. The art and science of total synthesis at the dawn of the twenty-first century. Nicolaou, K.C., Vourloxunis, D., Winssinger, N., Baran, P.S. (2000), Angew. Chem. Int. Ed., 39, 44-122. 

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