Alcohols 3-cyano, from epoxides

Epoxide ring-opening witli transfer of an sp carbon moiety was applied in a sbori syntliesis [44] of eicosanoid 56 [45], relevant in marine prostanoid biosyn-tliesis (Scheme 9.13). Honioallyl alcohol 55 was obtained in good yield from 54 by use of a cyano-G dman alketiylciiprate [46]. 

Then, nucleophilic aromatic substitution was applied for the synthesis of l,2,4,6,7,9-hexafluoro-l,4-dibenzodioxin from 2,3,4,6-tetrafluorophenol in the presence of sodium /-butylate <1995JFC(73)265>. In a similar way, cyano-1,4-dibenzodioxins and cyano-l,4-dibenzodithiins have been synthesized by fluorine displacement reactions with catechols <2001NJC379, 2001NJC385>. In accordance with a similar mechanism, the synthesis of spiro (l,4-benzodioxin-2,4 -piperidines) 205 and spiro (l,4-benzodioxin-2,3 -pyrrolidines) 206 have been developed from alcohols 207 and 208, respectively, both of them being obtained from 2-fluorophenol 210 with the corresponding epoxide 209 (Scheme 18) <2003SL813>. 

Construction of the suitably substituted geranic acid for making the furan ring has been effected too. For example, Poulter et al. have prepared the substituted geranate 865 by reaction of 4-methyl-3-pentenylcopper with the acetylenic ester 866. The ester 865 then underwent cyclization in the presence of acid to the lactone 867, related to scobinolide (161), and the action of acid on the lactol produced from 867 with diisobutylaluminum hydride gave perillene (849). The lactone 867 has also been prepared by a slightly different method the C9 alcohol 868 was made (in poor yield) from isobutenol and prenyl chloride with butyllithium. The extra carbon atom was introduced by the action of sodium cyanide on the epoxide of 868, and hydrolysis of the cyano group followed by dehydration yielded the lactone 867. The dimethylthioacetal of 867 has been used to synthesize perillene (849). This thioacetal was made from the suitably substituted ketene thioacetal 869 and dimethylsulfonium methylide. Thus the ketene thioacetal 870 (readily prepared from acetone, carbon disulfide, and sodium amylate, followed by methylation °) can be prenylated with lithium... 

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