2-ethoxy-3,5-hexadiene

Some reactions via intermediate alkylideneallyl cations have been reported. Solvolysis of 3-bromo-2,5-dimethyl-2,4-hexadiene in ethanol at 100 °C for 80 min gives 5-ethoxy-2,5-dimethyl-2,3-hexadiene in quantitative yield (Scheme 2) (5). This indicates that ethanol selectively attacks the sp2 carbon of the intermediate alkylideneallyl cation. A similar selectivity has been observed in the solvolysis of 2,3-dienyl alcohols (6), and is in agreement with the charge distribution. A cycloaddition reaction via an alkylideneallyl cation intermediate has been reported as illustrated in Scheme 3(7). 

Furan 2-Butyl-3-chlor-4,5-dihydro-E1S/1, 213 (H - C4H9) 1,3-Hexadien 3-Chlor-5-ethoxy-V/lc, 388... 

The compounds that we have identified from sorghum root extracts other than 1 are 5-ethoxysorgoleone (2), 2,5-dimethoxysorgoleone (3), 2-hydroxy-5-methoxy-3-[(8 Z, 11 Z, 14 Z-)-8, 1114 -heptadecatrienyI]-2,5-cyclohexadiene-1, 4-dione (4), 2-hydroxy-5-methoxy-3-[(8 Z,l rZ)-8, ll -pentadecadienyl]-2,5-cyc-lohexadiene-1,4-dione (5), 2-hydroxy-5-methoxy-3-[(8 Z)-8 -pentadecenyl]-2,5-cyclohexadiene-1,4-dione (6), 2-hydroxy-5-methoxy-3-pentadecyl-2,5-cycIo-hexadiene-1,4-dione, also known as dihydromaesanin (7), 4,6-dimethoxy-2-[(8 Z, 11 Z)-8, 1114 -pentadecatrienyl]-1,3-benzenediol (8), 4-methoxy-6-etho-xy-2-[(8 Z,irZ)-8, ir,14 -pentadecatrienyl]-l,3-benzenediol (9) and 6-ethoxy-3-[(10 Z,13 Z)-10, 13, 16 -heptadecatrienyl]-l,2,4-benzenetriol (10) (Fig. 3). 

Sorbic acid can be converted to 2-ethoxy-3,5-hexadiene by heterofermentative lactic acid bacteria. In concentrations of 0.1 m/1, this corr5>ound produces a geranium note. 

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