Nonaflates, Heck reaction

Heck-type reactions with enol carboxylates (e.g., vinyl acetate) are generally complex. Most common are reactions in which vinyl acetate is employed as an ethylene equivalent (see Scheme 24). However, an example of a preparatively useful reaction with an intact acetate function is given in entry 44.The reaction of vinyl triflates with vinyl phosphonates affords the corresponding conjugate dienylphosphonates (entry 45).f A new access to reactive nonaflates via a one-pot nonaflation-Heck reaction was recently reported (entry 46). " This reaction sequence starts from silyl enol ethers and provides functionalized 1,3-dienes in a simple manner, lodonium salts can be used as RPd precursors (entry 47). It is notable that the palladium(O) insertion preferentially occurs inbetween the iodonium ion and the vinylic, rather than the arylic sp -hybridized carbon (entry 47). Some years ago, Jeffery used acetylenic halides to achieve (JiJ-enynoates and (Ji)-enynones in fair yields at room temperature (entry 48). ... 

Webel, M. and Reissig, H.U. (1997) Heck reactions starting from silyl enol ethers. A simple one-pot nonaflation-coupUng procedure for the synthesis of 1,3-dienes. Synlett, 1141-2. 

Scheme 5-29. Halotri- and nonaflates synthesis and Heck reactions. ...

One of the key steps in this synthesis is the domino-ZZeck reaction forming 45.19 The Pd-catalyzed coupling of alkenes with vinyl- and aryliodides was discovered in 1968 by R. F. Heck nowadays also triflates or nonaflates are used as substrates.20... 

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