The Heck Reaction in Fine Chemicals Syntheses

The sunscreen agent 2-ethyUiexyl p-methoxycinnamate has been produced on a pilot plant scale by a Heck coupling of p-methoxyphenyl iodide with 2-ethylhexyl acrylate using palladium on charcoal as a catalyst [622]. Naproxen, a member of the arylacetic acid family of nonsteroidal anti-inflammatory drugs 

The same procedure can be applied for traws-4-fluorostilbene (480c) (93%), trans-4-methylstilbene (480d) (65%), trans-4-methoxystilbene (480e) (69%), tmns-4- luoro-4 -methoxystilbene (85%), trows-4,4 -dimethoxystilbene (30%) from the corresponding bromoarenes, and trans-4-cyanostilbene (480f) (48%) from 4-chloro-benzonitrile (7f-Cl). 

Methyl 3-( )- 2-[2-( ]-Methoxycarbonylethenyl]cyclopent-1-enyl acrylate (482b) 

The same procedure can be applied for the twofold coupling of 1,2-dibromocyclopentene (481) as well as 1,2-dibromocyclohejtene (213) with other acrylates, styrene, and substituted styrenes. Eor the coupling with ethenylsilanes, far better yields were obtained from 1,2-diiodocycloalkenes [625]. 

4) The authors suggest to run the Heck reactions in screw-capped Pyrex bottles to insure reproducible results, but caution and careful handling is advised in view of two explosions in the authors laboratory (one with bromobenzaldehyde (formation of CO), the other with Pd/C 

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