Williamson coupling

Dendrons have also been used as the capping moieties for rotaxane cores (Figure 8). Amabilino et al. reported the Williamson coupling of the third generation Frechet-type dendrons 6 to cap polyether macrocycles threaded around linear bipyridinium oligomers.241 When the linear component consisted of multiple viologen units, 171, shuttling of the... 

In addition to its uses in photography and medicine, iodine and its compounds have been much exploited in volumetric analysis (iodometry and iodimetry, p. 864). Organoiodine compounds have also played a notable part in the development of synthetic organic chemistry, being the first compounds used in A. W. von Hofmann s alkylation of amines (1850), A. W. Williamson s synthesis of ethers (1851), A. Wurtz s coupling reactions (1855) and V. Grignard s reagents (1900). 

Santos-Buelga, C., Garcia-Viguera, C., and Tomas-Barberan, F.A., On-line identification of flavonoids by HPLC coupled to diode array detection, in Methods in Polyphenol Analysis, Santos-Buelga, C. and Williamson, G., Eds., Royal Society of Chemistry, Cambridge, Chap. 5, 2003. 

New derivatives incorporating sucrose inside the backbone of a macrocycle have been prepared. The C-6 and C-6 ends in free sucrose are close to each other (see Scheme 2 in Section II. 1). They obviously are also close in partially protected sucrose (l -O-MOM or l -O-BOM derivatives of penta-(9-benzyl-sucrose) since they can be connected together by (at least) a C4 carbon bridge by a Williamson-type coupling of the sucrose diol with 1,4-diiodobutane (Scheme 33).310... 

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

Membrane fractions of several cell lines derived from immunocompetent cells were previously analyzed by photoaffinity labeling (Williamson et al., 1995) and the key enzyme in pyrimidine biosynthesis, DHODH, was identified as one of the major targets of Leflimomide. For further elucidation of its mode of action, the cytosolic fraction of the monocyte/macrophage cell line RAW 264.7 was subjected to affinity chromatography to identify all cytosolic binding partners of Leflunomide. The cytosolic preparation was applied to an affinity column where the Leflunomide derivative A 95 0277 was coupled as a ligand (Figure 10.2). 

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. 

Williamson" devised an experimental method to obtain coupling... 

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