References dihydrofurans

Although the synthesis of each chromophore material is to some extent unique (and hence requires individual description which is beyond the scope of this review), most chromophores used for device prototyping involve amine donor moieties. Thus, once a large quantity of aldehyde-terminated amine do-nor/partial bridge material has been synthesized, it can be reacted via Knoeve-nagel condensation with a variety of acceptor groups to form different series of chromophores. The acceptor in Schemes 1-4 is 3-cyano-5,5-dibutyl-2-dicy-anomethylene-4-methyl-2,5-dihydrofuran (which we refer to as the cyanofuran, CF, acceptor). This is synthesized by a literature method [213]. 

A fusion of Cso with a functionalized dihydrofuran is achieved by radical-mediated reaction of the fullerene with ketones. Again the process includes a radical intermediate with the highest spin density centered in direct vicinity to the site of initial attack. This turns ring closure into the most favorable reaction path (Figure 2.67). Ciso may also join into radical polymerizations (refer to Section 2.5.5.6). 

So far, enantioselective olefin metathesis has the largest impact on organic synthesis in the desymmetrization of achiral polyenes [81] an illustrative example refers to the total synthesis of endo-brevicomin [82]. The catalytic asymmetric cycli-zation of achiral trienes and meso-tetraenes via ARCM proceeds in excellent enan-tioselection (e.e. > 99 %) as demonstrated for dihydrofuran 163 (Scheme 11.40). 

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