2- tert- Butylfuran

Block copolymerization of IB with MeVE was also carried out using 2-methylfuran or 2-tert-butylfuran as a capping agent. However, the crossover efiidency was only... 

Katritzky and his colleagues have used equilibrium proto nation to estimate the aromaticity of furan and similar heterocycles using 2,5-di-tert-butylfuran as substrate in sulfuric acid. In agreement with the foregoing discussion, the furan does not behave as a Hammett (i.e., oxygen) base but as a carbon base similar to azulene. On Reagan s Hc scale, the furan gave n = 1.22, correspond-... 

One of the major areas of study in the photochemistry of heterocycles is the photorearrangement of five-membered heteroaromatic systems. Various mechanisms have been proposed to account for these transformations.123 A ring contraction-ring expansion pathway, via an intermediate cyclopropene, appears to be involved in the rearrangement of derivatives of furan. The isolation of an intermediate (140) of this type together with an allene (141) has been effected on irradiation of 2,4-di-tert-butylfuran (142), as shown in Scheme 9.124 Similar transformations have been reported in perfluorotri-... 

When 2,5-fc rf-bu tylthiophene S-oxide (688) is photoirradiated, 2,5-tert-butylfuran (689) is produced almost quantitatively. When 2,4-tert-butylthiophene S-oxide is photoirradiated, 2,4-ferf-butylfuran is isolated. Here, however, also side products can be observed. 

So far only one example of furan alkylation assisted by arene complexes has been reported. D.J. Milner has shown that furan reacts with tert-hutyl chloride in the presence of (TX -mesitylene)Mo(CO)3 to afford a mixture of 2-fert-butyl-furan and 2,5-di-tert-butylfuran in 65-80% yields [20]. Both mono- and disub-stituted furans can be prepared as the major product by changing the furan/t-BuCl ratio. Although there is only one report of this reaction, the ability to synthesize mono- and disubstituted furans in a simple manner reflects the potential of this methodology which can be used for preparing substituted furans, that are valuable synthetic materials. 

The chloromercuric derivative of furan is also suitable for alkylation. When tert-butyl bromide is added to the solution of this compound in chloroform, an exothermic reaction takes place. Three products were isolated from the reaction mixture, with 2,5-di-ieri-butylfuran in moderate yield131 ... 

After the isolation of a Dewar benzene substituted by tert-butyl groups, van Tamelen tried to isolate a Dewar furan stabilized by terr-butyl groups. However, the photolysis of di- or tri-fe/7-butylfuran did not give any Dewar compound but only cyclopropenyl ketones and its ring-opened products I04>. The reaction of di-fert-butylfuran is described by the following equation (104). 

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