Of 2,5-dimethyl furan

Incorporation of a furan moiety as a carbene wingtip group was introduced by Nielsen et al. The synthesis is facile enough starting with a bromination (NBS) of 2,5-dimethyl-furan and subsequent reaction with two equivalents of N-substituted imidazole to yield a bis-imidazolium furan [187] (see Figure 3.67). 

Elaborate kinetic analyses of the photo-oxygenation of 2,5-dimethyl-furan (22, 56) and allylthiourea (40) sensitized by xanthene dyes and chlorophyll, respectively, and of the direct photo-oxygenation of anthracene and 9,10-diphenylanthracene (41) have revealed that Type II direct and indirect (sensitized) photo-oxygenation reactions proceed with... 

Furan derivatives. Acetic anhydride added to a stirred soln. of 2,5-dimethyl-furan in benzene, then a soln. of SnGl4 in benzene added during 30 min. at 15-20°, stirring continued 1 hr. at the same temp. 3-acetyl-2,5-dimethylfuran. Y 87%. P. H. Williams et al.. Am. Soc. 82, 4883 (1960). 

Somers KP, Simmie JM, Gillespie F, et al. A comprehensive experimental and detailed chemical kinetic modeling smdy of 2,5-dimethyl furan pyrolysis and oxidation. Combust Flame. 2013 160 2291-2318. 

In order to establish the general validity of the mechanism of photosensitized oxygenation reactions, substrates other than 2,5-dimethyl-furan have been investigated.81 The quantum yield of product formation is given by the general equation... 

Cation 6 adds to furan, pyrrole, thiophene and some of their 2,4-dimethyl derivatives bearing a free a-position, in MeCN as solvent. Furan is the least reactive substrate giving 2-arylated product in 32% yield, whereas under the same reaction conditions the sulfur analogue provides 54% of 2-substituted-thiophene 9c (Scheme 10.37). Pyrroles are the most reactive heterocycles, and 2-arylated products 9a-b are found with 64% and 75% yields using pyrrole and 2,4-dimethyl-pyrrole, respectively. Only with 2,5-dimethylated furan and pyrrole, will arylation... 

Oxidation. As one step in the synthesis of furaneol (3, a flavor principle of pineapples and strawberries), Buchi et a . wished to effect hydroxylation of 2,5-dimethyl-2,5-dimethoxy-2,5-dihydrofurane (1). They tried oxidation of(1 15.8 mmole) with potassium chlorate (22.8 mmole) and osmium tetroxide (0.3 mmole) in aqueous letrahydro-furane containing sodium bicarbonate at 30° for 63 hr. however, the expected diol... 

Fig. 5. Hydrogenation of the ring of heterocyclic compounds using 1 g. of 5% Rh on AI2O3 powder as catalyst and 100 ml. solvent. 1) 1 ml. pyridine, H2O 2) 1 ml. pyrrole, HOAc 3) 1 ml. 2, 5-dimethyl-furane, HOAc 4) 1 g. furoic acid, H2O 5) 1 ml. furfuryl alcohol, H2O.

FIGURE 27-20 Microfabricated columns (a) and chromatogram (b). The columns in (a) were 0.9-m-long spiral and serpentine channels, The mixture (b) was 1, acetone 2. 2-butanone 3. benzene 4, trichloroethylene 5. 2,5-dimethyl-furan and 6. toluene. Air was used as the carrier gas with an outlet pressure of 0.5 atm. (From R. Sacks, in Modern Practice of Gas Chromatography, R. L. Grob and E. F. Barry, eds., 4th ed New York Wiley-Interscience. 2004. p. 269. With permission.)... 

Singlet oxygen reacts with fiufuryl alcohol (a 1,3-diene) and 2,5-dimethyl furan (also used as a probe) in what is termed by the organic chemist as a Diel s-Alder reaction to produce an endoperoxide that reacts further to give the products illustrated. The reaction with an alkyl substituted alkene involves abstraction of the allylic hydrogen and recombination to form an... 

A detailed kinetic model, based on quantum chemical calculations for the initial 2,5-dimethyl furan (2,5-DMF) consumption and important reactions of intermediates, is proposed for the oxidation of 2,5-DMF. The model is validated by comparison with new measurements of 2,5-DMF shock tube ignition delay time and its pyrolysis speciation measurements (/. Phys. Chem. A, 102, 10655 (1998))." " ... 

In addition to terpenes, carbohydrates serve as a precursor of furanones in plants. The formation of 2,5-dimethyl-4-hydroxy-2H-furan-3-one (DMHF) is an example. This compound, and various forms thereof, are key to the aroma of strawberry. Several researchers have studied the biochemical pathways responsible for the formation of this compound [34,35]. The pathway presented in Figure 4.10 illustrates DMHF formation from its key precursor, 6-deoxy-D-fructose. 

FIGURE 4.10 The biosynthetic pathway for the formation of furaneol and its derivatives in strawberry. (From Roscher, R., R Schreier, W. Schwab, Metabolism of 2,5-dimethyl-4-hydroxy-2H-furan-3-one in detached ripening strawberry fruits, J. Agric. Food Chem., 45(8), p. 3202, 1997. With permission.)... 

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