Total syntheses of cyclic halo ether compounds from marine origin

Abstract

This chapter discusses a variety of structurally unusual C15 nonisoprenoid metabolites that have been isolated from red algae as well as the molluscs that feed on them. The representatives are laurencin, dactylynes, laurenyne, isolaurepinnacin, and dactomelynes. Of these, laurencin is the most typical compound in respect of being the first natural product having an eight-membered cyclic ether. The significant biological activity of natural products containing eight-membered cyclic ethers as well as the well-known difficulties in forming medium sized rings have accelerated the development of new methodologies for constructing medium cyclic ethers. The chapter presents a new and general method for the conversion of lactones into substituted cyclic ethers via lactone enol triflates. This methodology provides a general procedure for the synthesis of various marine natural products including (+)–laurencin. This methodology is applied in the synthesis of (+)–lauthisan, which is an artificial compound derived from natural laurencin (+)–1 by chemical reactions.