1 -Pheny 1-4- naphthalene

The versatility of poly(phenylcne) chemistry can also be seen in that it constitutes a platform for the design of other conjugated polymers with aromatic building blocks. Thus, one can proceed from 1,4- to 1,3-, and 1,2-phenylene compounds, and the benzene block can also be replaced by other aromatic cores such as naphthalene or anthracene, helerocyclcs such as thiophene or pyridine as well as by their substituted or bridged derivatives. Conceptually, poly(pheny ene)s can also be regarded as the parent structure of a series of related polymers which arc obtained not by linking the phenylene units directly, but by incorporation of other conjugated, e.g. olefinic or acetylenic, moieties. 

Stevani and coworkers prepared and characterized a peracid intermediate, 4-chloro-pheny 1-0,0-hydrogen monoperoxalate (57) and found that no chemiluminescence was observed in the presence of activators (i.e. rubrene, perylene and DPA) and the absence of a base. Based on this result, the authors excluded 57 and similar peracid derivatives as HEI in the peroxyoxalate system. Moreover, 57 only emits light in the presence of an activator and a base with pK > 6, suggesting that a slow chemical transformation must still occur prior to the chemiexcitation step. Kinetic experiments with 57, using mainly imidazole, but also in the presence of other bases such as potassium 4-chlorophenolate, f-butoxide and l,8-bis(dimethylamino)naphthalene , showed that imidazole can act competitively as base and nucleophilic catalyst (Scheme 41). At low imidazole concentrations, base catalysis is the main pathway (steps 1 and 2) however, increasing the base concentration causes nucleophilic attack of imidazole catalyzed by imidazole to become the main pathway (steps la and 2a). Contrary to the proposal of Hohman and coworkers , the... 

Quite interestingly, the minor product 2-pheny 1-2,5-dihydrofuran (200) has the opposite configuration, i.e., (5)-200, compared to that of (/ )-199. However, this compound is produced with a significantly lower enantiomeric excess. It is possible that this is caused by a kinetic resolution effect in the alkene complex 205 the jr-bound hydridopalladium moiety in complex 205 could add again to the double bond. Base influence is also noteworthy, and the highest enantiomeric excess was achieved with l,8-bis(bisdimethylamino)naphthalene ( proton sponge ). 

Chen and Lu used a mercuric acetate-mediated annulation of homopropargylic alcohols to generate iodinated furans for use in crosscoupling reactions. Treatment of 2-(3-methylbut-1 -yn-1 -yl)-2-pheny 1-1,3-dithiolane with nBuLi, followed by reaction with -butylaldehyde, produced a mercuric acetate intermediate that was subsequently trapped with iodine to give the corresponding 3-iodofiian. Further cross-coupling with a series of compounds (in this example naphthalene) led to the desired tetrasubstituted fiiran in 87% yield over three steps. 

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