- The Williamson Reaction: A New and Efficient Method for the Alternate Reaction of 2,2'-Bis(bromomethyl)-1,1'-binaphthyl and 1,1'-Binaphthalene-2,2'-diol
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Treatment of 2,2'-bis(bromomethyl)-1,1'-binaphthyl with 1,1'-binaphthalene-2,2'-diol (+)-(R)-1 and cesium or potassium carbonate in refluxing acetone, gave the diastereomeric dioxacyclophanes (-)-(R,S)-3a and (+)-(R,R)-3b, both obtained in high yield, and the cyclic tetraether (+)-(R,R,R,S)-4 as isolated side product.Boron tribromide-promoted ether cleavage of 3a and 3b gave optically pure (-)-S-2 and (+)-(R)-2, respectively, and the recovered diol (+)-(R)-1.Alternatively, the same reaction sequence furnished the resolved diols (-)-(S)-1 and (+)-(R)-1 from (R,S)-1 and (+)-R-2, as well as optically pure 2,2'-bis(chloromethyl)-1,1'-binaphthyl (+)-(R)-5 from the racemic dibromide (R,S)-2 by using boron trichloride for ether cleavage.
- Mazaleyrat, Jean-Paul,Wakselman, Michel
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p. 2695 - 2698
(2007/10/03)
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