Williamson etherification

Cyclohexene-1 -methanol undergoes smooth Williamson etherification with a,co-dibromoalkanes in the presence of base and a phase transfer catalyst. The resulting biscyclohexenyl ethers, XXIIa-e, were subsequently treated with m-chloroperoxybenzoic acid to give the desired diepoxide monomers, XXIIIa-e. Table 3 gives the characteristics of these monomers. 

The major difference between our reaction conditions and the conventional phase transfer catalyzed Williamson etherification (22) is the use of stoichiometric amounts of phase transfer catalyst versus the nucleophilic chain ends in the former case. Under these... 

In conclusion, phase transfer catalyzed Williamson etherification and Wittig vinylation provided convenient methods for the synthesis of polyaromatics with terminal or pendant styrene-type vinyl groups. Both these polyaromatics appear to be a very promising class of thermally reactive oligomers which can be used to tailor the physical properties of the thermally obtained networks. Research is in progress in order to further elucidate the thermal polymerization mechanism and to exploit the thermodynamic reversibility of this curing reaction. 

Scheme 33. Coupling at the 6,6 -positions of partially protected sucrose by Williamson etherification.

Takahashi et al. also reported a route to muconin. Their synthesis adopted Keinan et al. s strategy to construct the stereochemistries by Sharpless AD and AE upon multiple olefin containing fatty acid (Scheme 10-35). The di-olefin 214 was subject to Sharpless AD conditions and then treated with acid, yielding a THP-containing diol. This diol was further protected as acetonide 215. The reversion of stereochemistry of alcohol 215 was achieved by Dess-Marlin oxidation and Zn(BH4)2 reduction. Williamson etherification of tosylate 216 and epoxide formation afforded tri-ring intermediate 217. Opening with acetylene, 217 was converted into the terminal alkyne 218, which was coupled with vinyl iodide to finally give muconin. 

R)- and (S)-l,l -bi-naphthyl-2,2 -di-[pflrfl-(frflMS-4-M-pentylcyclohexyl)phenoxy-l-hexyl]ether were synthesized through the Williamson etherification reactions of chiroptical ( )-(+)- and (S)-(—)-l,l -bi-2-naphthols, respectively, with phenylcyclohexyl (PCH) derivatives. The products will hereafter be abbreviated as R)- and (S)-PCH506-Binol (Scheme 3.1). The suhstituent is composed of PCH moiety, M-pentyl group (the number of carbon of 5), and hexamethylene chain linked with an ether-type oxygen atom, [-(CH2)sO-, 06], hence abbreviated as PCH506. 

Figure 4. The Williamson etherification of 2-norbomene-5-exo-ylmethyl tosylate with tetraethylene glycol produces the water soluble monomer (4). The norbomene compounds shown are racemates.

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